NL9000258A - ENDLESS ARTICLES OF ACRYLATES. - Google Patents

Description

Inventor: Cornells W.M. Bastiaansen in Geleen

ENDLESS ARTICLES OF ACRYLATES

The invention relates to a composition containing oligomeric acrylates, of which endless objects can be made without the use of carrier material.

In this description, endless objects are understood to mean objects which have an almost infinite length in at least one direction, such as fibers, foils and tubes. By a carrier material is meant material that is virtually infinitely long, such as fibers or foils, which is used to apply and subsequently cure the composition containing acrylates.

A composition from which endless objects can be made without the use of carrier material is described in JP-61262707.

This describes a composition based on acrylates, which can be processed by special treatment into endless objects, in particular into optical fibers. To achieve this, an arrangement is being built in which an acrylic mixture is pressed through a tube, whereby the acrylates partially harden in the tube, after which the partially cured acrylates are spun and further cured.

The drawback of a composition as described in JP-61262707 is that a complicated operation is required to continuously process the oligomeric acrylates, because the acrylates have to be partially cured but not reach their gel point. The range within which the acrylates can be continuously processed is therefore quite narrow. This requires precise tuning of process conditions and continuous monitoring of the degree of curing during transport through the pipe. The result is that it is a very slow, cumbersome and therefore expensive process, and in any case very susceptible to failure.

The object of the invention is to provide a composition which does not have the above drawbacks.

This is achieved according to the invention in that the composition also contains a high molecular weight thermoplastic polymer.

High molecular weight (HMW) is meant here to be higher than 50,000. Preferably, the molecular weight of the thermoplastic is much higher than 50,000. When the thermoplastic has a molecular weight of more than 250,000, we speak of ultra high molecular weight (UHMW).

By mixing in HMW thermoplastic, the composition can be processed and shaped in an extruder, for example. In addition, the composition can be provided. This can be done in one or two directions. This can be used to make fibers or films, for example.

A further difference between JP-61262707 and the invention is that the composition according to the invention only needs to be cured after spinning or processing in the extruder, while the composition according to JP-61262707 is already partly cured before spinning.

Spinability will be used as a criterion for continuous processability in the manner outlined here. Spinability is a difficult concept to quantify, but this definition will use the definition given by Ziabicki in Fundamentals of Fiber Formation, J. Wiley & Sons Ltd., London, 1976: "A liquid is spinnable under the given conditions if a steady state, continuous elongation of the fluid can occur without any breakage occurring. "

The "given circumstances" here mean the conditions optimized by those skilled in the art.

Spinability is determined in the experiments by determining whether a wire picked up from a quantity of test material with a glass rod can be elongated and wrapped around an axis. This test is described by ziabicki in the same reference.

The degree of change in spinnability depends, inter alia, on the molecular weight of the thermoplastic. The higher the molecular weight, the less has to be added to increase the viscosity by a certain amount so that the composition becomes spinnable.

The composition preferably contains at least 0.1% by weight of the entire thermoplastic composition having a MW of greater than 5,000,000 to 50% by weight with a MW of 50,000.

The minimum amount of thermoplastic to be added to obtain a continuously processable composition also depends on the type of thermoplastic: for example, a branched thermoplastic will generally require more than a linear thermoplastic. In general, the properties of the composition sought will be determined by the average chain length of the thermoplastic polymer dissolved therein. This means that, for example, polyethylene oxide has a lower weight percentage with a specific molecular weight than polyvinyl acetate, because PEO per unit chain length is less heavy than PVAc.

It is possible to add higher percentages of thermoplastic. However, the properties of the product can be adversely affected by the thermoplastic. Therefore, it is usually desirable to keep the amount of thermoplastic as small as possible.

The admixture of a thermoplastic in a polymerization liquid to increase the viscosity has already been described in U.S. Pat. No. 1,057,434, but it does not mention oligomeric acrylates. This patent aims to solve the problem of not dissolving a polymer in its own monomers. There is no suggestion in the patent that it would also work with thermosetting systems based on oligomeric acrylates.

Although the patent also describes the possibility that a small amount of monomer can be added to the Newtonian liquid of mainly acryionitrile, which can ensure a certain degree of cross-linking, this only achieves a low cross-link density. Therefore, a product produced according to the method of this US patent will not have the excellent properties that a product according to the invention has.

A second known way of making endless objects from acrylates is by coating carrier material such as continuous or serai-continuous fibers with acrylates. It is practically not possible to stretch the objects with objects with carrier fiber. The material is then processed by coextrusion or pultrusion.

The thermoplastics can be selected from any high molecular weight thermoplastics which are compatible (ie at least partially soluble in) with the acrylate to be used, such as polyethylene oxide, polypropylene oxide, styrene-maleic anhydride-acrylonitrile copolymer, polyacrylate or polyvinyl acetate. Preferred polymers are available which have extremely high molecular weights, such as polyethylene oxide or polyvinyl acetate.

As acrylates, di- or higher functional acrylates or methacrylates are preferably used.

The acrylates can be selected from oligoethers, esters, or amides with 2 or more (meth) acrylate groups. Preferably, oligoethers or esters are used, such as, for example, alkoxylated bisphenol-A, polypropylene glycol or isophthalic acid-based oligoester.

The thermoplastic should at least partially dissolve in the oligomeric acrylates. Depending on the choice of the thermoplastic and the acrylates and the speed of curing, a molecular blend is created during the curing or phase separation takes place. The latter can result in favorable properties, such as an improvement in the toughness of the end product. This can be caused by the glass transition temperature (Tg) of the thermoplastic being lower than the operating temperature.

Low molecular thermoplastics can further be added to the composition to improve certain properties, such as impact strength.

The usual additives may further be added to the composition, such as inhibitors, promoters, accelerators, flexibilizers, lubricants, release agents, antioxidants, pigments, surfactants, crosslinkers, fillers or fiber reinforcements.

Curing initiation can take place in any way that acrylates can cure, such as thermally, with ultraviolet light, with other electromagnetic radiation, or by electron or gamma irradiation.

Preferably, the curing takes place under the influence of ultraviolet light, because the curing can then take place in a simple manner. Furthermore, the time can then be chosen freely: during or after the shaping process or in the cooling phase. An additional advantage is that high temperatures are then possible during suspending, dissolving and extruding or spinning, without the curing already starting.

A possible method for a process to make products could look like this:

The thermoplastic is suspended in the acrylates and dissolved. For this it may be necessary to heat the composition to a suitable temperature, for example between 50 and 200 ° C. The mixture is then extruded or spun and then half or completely cured.

Additional steps in this process can be to blend fibers into the composition and draw the extruded or spun semi-finished product.

Depending on the chosen processing method, the viscoelasticity of the composition can be adjusted. If spinning in the downward direction is chosen, a lower weight percentage or a lower molecular weight thermoplastic will suffice than, for example, in foil blowing in the upward direction.

If you want to produce thin objects, it is recommended to draw the composition before curing. If fibrous fillers have been added, and it is desired to see them oriented in the product, it is also recommended to draw prior to curing. If anisoptropy is desired in the final product, it is preferable to draw after or during curing.

If the curing of the acrylates takes place under supply of heat, the viscoelasticity of the semi-finished product will decrease and the semi-finished product will be able to experience an undesired stretch, inter alia due to gravity. This can be corrected for by allowing the curing to take place in a bath filled with a liquid inert during the curing reaction with a specific weight which is substantially equal to the specific weight of the composition.

It is possible to allow the reaction to take place under the influence of a catalyst which is contained in the inert liquid and diffuses into the composition from there.

Depending on the starting materials, products made from a composition according to the invention are suitable for applications in those areas where good temperature resistance, good fire resistance and / or good corrosion and solvent resistance are required in addition to good mechanical properties. Examples include cable sheathing, fireproof clothing, ashtray replacements, high temperature filters, aircraft interiors, carbon fiber precursors, food packaging (e.g., microwave oven), condenser films, optical fiber, and filament winding. It is of great advantage here that the acrylic resin compositions according to the invention do not have to be processed at a high temperature, which is necessary for thermoplastics with a high temperature resistance. In particular, the invention is advantageous where films, films, fibers, tubes, or other endless objects with one or more of the qualities described above are required. The products can be further produced as a bundle of thin filaments or as a thicker monofilament. It is possible to reduce products according to the invention by cutting, sawing, breaking or the like methods into products of a shorter length.

The invention will be illustrated by the following examples and comparative experiments, without being limited thereto.

Fiber tensile tests were performed at room temperature on a Zwick tensile testing machine equipped with fiber clamps. The starting length of the fiber was 50 cm, and the bank speed was 5 cm / min. The E-modulus, the tensile strength and the elongation at break are determined from the measured stress-elongation curve.

The manufacturer's specification was used for the molecular weight of the thermoplastic.

LOI measurements were made according to ASTM-D2863.

DMA measurements were performed according to M.E. Brówn,

Introduction to Thermal Analysis, Chapter 8, page 72 and further.

TGA measurements and DSC measurements were performed according to F.W. Billmeyer, Textbook of Polymer Science, John Wiley and Sons, ISBM 0 441 072966.

Experiments I to III Determination of the percentages of thermoplastic required for spinnability.

Polyethylene oxide (PEO) was obtained from Aldrich Chemie, W-Germany with molecular weights 200,000, 900,000 and 5,000,000 according to the manufacturer's specification.

The epoxy acrylate resin was Ebecryl 600 from Radcure Specialties, Belgium.

Three different molecular weights of PEO were suspended in the epoxy acrylate resin in various concentrations at room temperature. The different molecular weights and concentrations are shown in Tables 1 through 3. The PEO was dissolved in the resin at a temperature of 120 ° C in a Brabender kneader.

The solution was transferred to dishes after which the dishes were brought to 3 different temperatures, viz. Example I 23 ° C, Example II 60 ° C and Example III 120 ° C.

An attempt was made to pick up a thread of material from each dish using a glass rod, after which an attempt was made to wind this thread around a horizontal axis placed above the dish. After this, the spindle was put in a slow spinning motion, continuously pulling the wire out of solution and wrapping it around the spindle. With moderate spinnability, the following tables mean that it was only possible after several attempts and very careful handling to pick up such a wire from the solution, wrap it around the shaft and turn the shaft.

Table 1 Spinability at 23 ° C.

Exp. I Molecular weight Concentration Spinnability tgr / mol] thermoplastic [% w / w] a 200,000 1 ± b 5 + c 10 ++ d 20 ++ e 900,000 0.1 ± f 1.1 + g 2.5 ++ h 5, 0 ++ i 10.0 ++ j 5,000,000 0.1 ++ k 0.2 ++ 1 0.5 ++ m 1.0 ++

The concentration of the thermoplastic is given in percent by weight relative to the total composition. Spinability is measured according to the test method described above, where - means very poorly spinnable, - means poorly spinnable, + means poorly spinnable, + means well-spinnable and ++ means very well-spinnable.

Table 2 Spinability at 60 ° C

Exp. II Molecular weight Concentration Spinability [gr / mol] thermoplastic [% w / w] a 200,000 1 b 5 c 10 ± d 20 ++ e 900,000 0.1 f 1.1 g 2.5 + h 5.0 + 10.0 ++ j 5,000. 000 0.1 ± k 0.2 + 1 0.5 ++ m 1.0 ++

Index see table 1.

Table 3 Spinability at 120 ° C

Exp. III Molecular weight Concentration Spinability [gr / mol] thermoplastic (% w / w) a 200,000 1 b 5 - c 10 d 20 ± e 900,000 0.1 f 1.1 g 2.5 h 5.0 i 10.0 + j 5,000,000 0.1 ± k 0.2 + 1 0.5 ++ m 1.0 ++

Index see table 1.

The tables show that a higher percentage of thermoplastic thermoplastic is required to spin the solution than of lower molecular weight thermoplastic.

By comparing the tables, it can be seen that at higher processing temperatures, relatively more must be added to make the solution spinable.

The invention preferably relates to a composition which contains such a large percentage of thermoplastics of a certain molecular weight that the composition is spinnable at the processing temperature for the composition. That is, at a desired processing temperature of 23 ° C, the composition contains at least 1% w / w of a thermoplastic having a molecular weight of 200,000.

At a required processing temperature of 60 ° C, the composition preferably contains 10% w / w of the thermoplastic with a molecular weight of 200,000.

At a desired processing temperature of 120 ° C, the composition preferably contains 20% of the thermoplastic having a molecular weight of 200,000.

However, the amounts described above apply here to PEO with the given acrylate. When using other acrylate-containing compositions and / or other HMW polymers, the numbers are likely to show a different picture. The guidelines described above give a clear indication of how the invention can be applied in analogous cases.

Comparative experiment A

The procedure of Examples I to III was repeated without mixing PEO in the epoxy acrylate. Again it was investigated whether the solution can be spun into a fiber at a temperature of 23, 60 or 120 ° C. This was not so.

Example IV

The procedure of Example II was repeated whereby

O

polyvinyl acetate (PVAc, Mowilith 70 from Hoechst Aktiengesellschaft, W-Germany) in epoxy acrylate was suspended and dissolved. The molecular weight of PVAc was g 1 * 10 and the concentration 15%. It was investigated whether the solution can be spun into a fiber. This appears to be possible.

Example V

The solution of Example I was mixed with 3

D

wt% UV initiator (Irganox 651 from Ciba-Geigy, France). The solution was transferred to a spinning vessel and spun at 100 ° C. The spun fiber was cured immediately after spinning by passing it under a UV lamp and was then wound on a spinning drum. The fiber was then thermally post-cured for 30 min at 160 ° C. The fiber has an E-modulus of 2.4 GPa, a tensile strength of 60 MPa and an elongation at break of 5%.

The solution with UV initiator was also subjected to a DSC measurement with a heating rate of 10 ° C / min. Thermal curing was only found to start at 195 ° C. Moreover, the solution was found to have little or no curing reaction when heated to 175 ° C for 60 minutes. The maximum processing temperature before and during spinning is thus about 175 ° C for this mixture.

Comparative experiment B

In the same manner as in Example V, an attempt was made to spin a fiber with epoxy acrylate, but without PEO being dissolved in it. This turned out to be impossible.

Example VI

The solution of Example V with 5 wt% UV initiator was poured into a plate and UV cured for 3 min at 80 ° C and thermally post cured for 30 min at 160 ° C. TGA measurements were made on the material obtained at a heating rate of 10 ° C / min in oxygen and helium. The weight loss was found to be less than 1% at temperatures up to 350 ° C. An LOI measurement was performed on the material. The LOI was 26%. A DMA measurement was made on the material. The Tg was 130 ° C.

Comparative experiment C

In the same manner as in Example VI, TGA measurements were made on epoxy acrylate with UV initiator without PEO. The weight loss was found to be less than 1% at temperatures up to 350 ° C. The LOI was 26%.

Claims (17)

A composition containing oligomeric acrylates from which endless objects can be made without the use of a continuous support material, characterized in that the composition also contains a high molecular weight thermoplastic polymer. Composition according to claim 1, characterized in that the thermoplastic is dissolved in the acrylates. A composition according to any one of claims 1-2, characterized in that the composition contains 0.1% by weight of the entire composition of the thermoplastic polymer with a molecular weight above 5,000,000 to 50% by weight of the thermoplastic polymer with a molecular weight of 50,000. The composition according to claim 3, characterized in that the composition contains at least 0.1% by weight of the entire composition of the thermoplastic polymer with a molecular weight above 5,000,000 to at least 2.5% by weight of the thermoplastic polymer with a molecular weight of 900,000. Composition according to any one of claims 1 to 4, characterized in that the oligomeric acrylates are selected from the group consisting of epoxy acrylates, hydroxy acrylates, carboxy acrylates and acrylamide copolymers. Composition according to any one of claims 1 to 5, characterized in that the thermoplastic is selected from the group consisting of polyethylene oxide, polyamide, styrene-maleic anhydride-acrylonitrile copolymers, polypropoxide, polyvinyl alcohol and polyvinyl acetate. Composition according to any one of claims 1-6, characterized in that the composition contains fibrous material. A method for making an endless article without the use of a continuous carrier material, characterized in that a composition according to any one of claims 1-7 is heated to a suitable temperature, the thermoplastic is dissolved at least in part, the composition is extruded or spun and then at least partially cured. Method according to claim 8, characterized in that the full or partial curing of the oligomeric acrylates takes place in a bath filled with a liquid inert during the curing reaction of a specific weight which is substantially equal to the specific weight of the composition. Process according to claim 9, characterized in that the inert liquid contains a catalyst suitable for curing oligomeric acrylates which can diffuse from the liquid into the composition. A method according to claim 8, characterized in that the composition contains a UV initiator and is cured by exposing the composition to UV radiation. A method according to any one of claims 8-11, characterized in that the composition is stretched unaxially or biaxially before, during or after at least partial curing of the oligomeric acrylates. Method according to claim 12, characterized in that the composition is stretched unaxially to a fiber with a thickness of less than 1 mm. A method according to claim 12, characterized in that the composition is biaxially stretched into a foil with a thickness of less than 1 mm. Method according to any one of claims 8-14, characterized in that the composition is post-cured. An endless article obtained by at least partial curing of a composition according to any one of claims 1-7, or by using a method according to any one of claims 8-15. 17. Composition as substantially described in the description introduction and examples.