WO2007147224A2

WO2007147224A2 - Acrylic and modacrylic polymer fusion process derivated from acrylonitrile and molded articles made from the same

Info

Publication number: WO2007147224A2
Application number: PCT/BR2007/000162
Authority: WO
Inventors: Nilton Pereira Alves
Original assignee: Nilton Pereira Alves
Priority date: 2006-06-19
Filing date: 2007-06-18
Publication date: 2007-12-27
Also published as: BRPI0602706A; WO2007147224A3; BRPI0602706B1

Abstract

Acrylonitrile polymers homo or copolymerized with different kinds of monomers are fused in non-solvents charaterized by high polarity and high ebullition points like glycols and mixtures of them. After the fusion the polymers are transferred to an extruder where the polymers are formed in filaments and other kind of desired subjects, such as tubes, billet and plates.

Description

"ACRYLIC AND MODACRYLIC POLYMER FUSION PROCESS, ACRYLIC AND

MODACRYLIC POLYMER, ACRYLIC AND MODACRYLIC POLYMER COMPOSITION AND ACRYLIC AND MODACRYLIC POLYMER USAGE"

INVENTION FIELD The present invention deals with the acrylic and modacrylic polymer fusion process that derive from acrylonitrile mainly with applications in the manufacturing of fibers and extrusion molded objects such as tubes billet and plates.

INVENTION'S BACKGROUND

It is known that, when heated, the polyacrylonitrile (PAN) homo and copolymerized with many monomers, more commonly: vinil acet, estiren, methyl methacrylate, methyl acrylate, causes the nitrylic group nitrogen to crystallize and as a consequence provokes the formation of crossed links or reticulation in the polymeric chain, not allowing the polymer fusion. As a result we have a degraded product with the total loss of the original polimer fisical and mechanical proprieties. This poliacrylonitrile characteristic causes the manufacturing of fibers process to be done using traditional and old processes in which, along the last decades, few improvements have been introduced. In the wet spinning process the poliacrylonitrile dissolution is made in a highly polar solvent, being the most used the dimethylformamide (DMF), dimethylacetamide (DMAc), the solution of ammonium thiocyanate, zinc chloride, and also nitric acid.

In these processes the poliacrylonitrile is dissolved in a solvent, in the concentration which allows the suitable viscosity for it's bombing though spinneret, immerse in a typically aqueous coagulation bath. The formed filaments are stretched and dried. The poliacrylonitrile solution process without coagulation is also used. Process in which the solvent is caused to evaporate after the filaments have come out of the spinneret (dry spinning). Due to economical reasons in both processes the used solvents recovery and recycling is necessary. Environmental aspects also make the process more expensive.

Being highly polluting for water and soil, none of the generated waste can be discharged in the environment. Factors related to the occupational hygiene of these plants' operators cannot be neglected due to the toxicity of these solvents.

The manufacturing process of poliacrylonitrile fibers by extrusion offers great advantage over the conventional process since it allows a great cost reduction for not using, or rather using low quantities of solvent. As a result these fibers can have non textile usages like asbestos substitutes, heat isolation, stiffening for cement and heat resistant fibers.

With the purpous of manufacturing acrylic and modacrylic fibers by extrusion process the existing published patents describe processes based on: a) Usage of fusible acrylic polymers

The patents US 5,602,222 e US 5,618,901 describe the obtaining of fusible acrylic polymers from the co-polimerisation of acrylonitrile with diverse many comonomers like metacrylonitrile, estiren, vinil acet, methyl methacrylate, methyl acrylate, polymerized in the presence of emulsifiers alkyl mercaptan and ammonium persulfate as a starter . The polymers obtained in the polymerization conditions which are described in these patents show thermal, physical and mechanical proprieties that are adequate to the extrusion and can be commercially found with the brands Barex® and Amilon®. These polymers disadvantage is the high cost that makes many of its applications to become not viable. b) Poliacrylonitrile (PAN) Fusion

Many patents like US 5,589,264 e US 5,434,002 describe the obtaining of acrylic and modacrylic fibers by the extrusion of a gel made out of a mixture of poliacrylonitrile and water fused at high pressure. The Opferkuch e Ross (US 3,388,202 of 1968) were the firsts to discover the poliacrylonitrile fusibility when mixed with water and put under high pressure in a closed reactor. At these conditions the poliacrylonitrile's temperature remains below its degradation temperature which allows the extrusion and conformation. The patent US 3,984,601 de 1976 (DuPont) describes the adequate concentrations of water and acrylic copolymers for the manufacturing of filaments and (cling) films. It also describes the extrusion conditions and the proprieties of the obtained filaments.

The English patent GB 1 ,327,140 describes the obtaining of acrylic fibers by the polymer pre-molding at high temperature and pressure. Dark brown color fibers were obtained by this process.

Therefore, through researches and studies directed to the polymers fusion, the Applicant, came to the objectives describes here as a new fusion process of acrylic polymers. Both reported processes present many economical and technical hold backs which have not been overcome yet and make the obtained fibers not competitive with the ones obtained by the current wet spinning and dry spinning.

The raw material cost, polymerization time span, continuous process polymerization difficulties, difficulties with the polymer flocculation when in emulsion state, make the fusible acrylic and modacrylic polymers economically not viable for textile or not textile applications when compared to the ones obtained in conventional processes.

As per processes involving the poliacrylonitrile fusion with water under pressure, it is difficult to transform them in continuous processes, considering that the possibility of the acrylic and modacrylic polymer fusion under its degradation temperature was only shown from the technical point of view so far, but that has not allowed it's industrial application yet. INVENTION DESCRIPTION

The present invention highlights fusion of the acrylic and modacrylic polymer complying the following steps: (I) preparing the fusion and thermal transference means containing a high polarity non-solvent liquid; (II) to heat the polymer's fusion temperature; (III) to obtain a fused polymer mass; (IV) to subject step (III) to an extrusion process; (V) and to obtain the desired polymer's shape.

In the present invention we solved the poliacrylonitrile fusing problem in normal conditions of pressure, making its fusion in a highly polar non-solvent liquid with high ebullition point. The fused poliacrylonitrile's mass in this means can be transferred to an extruder and conformed in filaments or in any desired shape.

As a liquid means o fusion it is a non-solvent polymer, its consume is very little if compared with the traditional wet spinning and dry spinning processes.

Another relevant aspect of the present invention is the non-solvent of the polymers used in the fusion are of a low environmental and biological toxicity when compared with the typical solvents in traditional processes as dimethylformamide, dimethylacetamide.

This invention is based on the finding that polymers that are comprised of poliacrylonitrile co-polymerized with different monomers are fused in highly polar means as the glycols. Being the means highly polar, it bars the cyclization of the nitrogen of the nitric grouping causing the polymer's fusion.

Without the nitrogen stabilization the poliacrylonitrile cyclization starts in approximately 180° C with great energy dissipation which can easily be observed by DSC. This cyclization occurs as in the presence of an air as it does in inert gas. It is reported that ionic species that are present in the polymer can act as starters, considerably altering the temperature where the cyclization occurs. See below an example of the poliacrylonitrile cyclization process:

18O ⁰C

The reaction is very quick and exothermical and the cyclization can be noticed by the polymer's change of color. During the cyclization the polymer that is initially white, becomes yellowish, orange and in the end dark brown with cracky characteristics and it is not fusible. The cyclization can also occur among different polymeric chains, resulting tridimensional entwines. This poliacrylonitrile propriety is used for obtaining high temperature resistant carbon fibers.

The products that are liberated during cyclization can be ammonia, water and cyanide acid.

The present invention's polymers have over 35% unites that derive from acrylonitrile co-polimerized with one or more comonomers represented by acrylic units like:

(— CH₂^H- ).

I

CN Na acrylic polymer is chemically defined as having more than 85% acrylonitrile units. Modacrylics are the polymers that have form 35% to 85% in acrylonitrile weight units. Possibly, the solving of the poliacrylonitrile molecule in highly polar solvents like water, alcohols and glycols causes the nytrilic nitrogen dipole to be preferably attracted by these substances hydrogen dipoles, therefore barring the formation of liaisons with neighboring carbons and the cyclization of the chain. Such glycols are selected between the alcohols that contain two or more hydroxyles per molecule and between them we can highlight the most common ones like the ethylene glycol, diethyl glycol, Triethylene glycol, polyethylene glycol, propylene glycol, butylene glycol and glycerol.

Even with the poliacrylonitrile long drawn out heating on glycol its cyclization occurs in 5 to 10 minutes of the fusion.

This permanence time of the fused poliacrylonitrile is too short for its processing in extruders and we found out that the poliacrylonitrile can remain fused without cyclization for hours if some additives like high ebullition point inorganic acids are added in small concentrations to the glycol which is time enough to allow its continuous processing.

We proved through infrared analysis that the poliacrylonitrile co-polymerized at 6%, vinil acet did not present cyclization even after remaining fused for 100 minutes in a mixture of monoethylene glycolat 48%, diethyl glycol at 48% and phosphoric acid at 4%. In picture 1 , we can see the PAN comparative infrared spectra before and after fusion, according to the transmittance and the number of waves measured in cm^"1.

The strong band observed in 2. 240cm^"1 corresponds to the stretching of the group CsN and tends to reduce intensity during cyclization. The observed frequencies between 1.700 and 1.000 cm^"1 especially in 1740 cm^"1 corresponding to the stretching of the group C=O deriving from the comonomer vinil acet. Duringcyclization the formation of C=O groupings occur, which makes this band's intensity increase. The groupings which can be formed during cyciization tend to increase intensity.

The spectrum A corresponds to the original poliacrylonitrile copolymerized at vinil acet at 6% in the form of film obtained by the dissolution of the DMF polymer and drying at 105⁰C.

The spectrum B corresponds to the same polymer's sample which was kept in fusion at 190⁰C for 100 minutes in the ethylene glycol/ diethyl glycol/ phosphoric acid mixture. We can notice in these comparative spectra that the cyciization level was small in the fused PAN sample because the frequency that corresponds to C≡N continued very intense and on top of that the mass viscosity remained satisfactory for the extrusion in filaments that showed a pale yellow color.

Picture 2 represents a picture of the PAN fusion equipment.

EXAMPLES

The examples presented in this invention are merely illustrative, they were given In order to better show one of our favorite accomplishments which is representative but not limitative to the performed experiments.

EXAMPLE 1

Approximately 100,0 g of PAN copolymerized at 6% vinil acet was added to

1.00Og of a mixture containing 975g of monoethylene glycol (MEG) and 25g phosphoric acid at 85% kept at 19O⁰C +/- 2⁰C. After 5 minutes shaking (agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface and mechanically transferred to the extruder.

The fused mass was extruded at 190⁰C at 30lb/hour (30 pound/hour) through the dry spinning of 120 μm/1.000 holes. The obtained filaments were stored at 12O⁰C for 5 minutes and after that were cooled an room temperature. They presented bright light yellow color with 32 dtex: Picture 3 represents 32 dtex filaments that were obtained as example 1 describes.

EXAMPLE 2

Approximately 100,Og of PAN copolymerized with 10% estiren were added in 1000g of a mixture containing 487, 5g of monoethylene glycol (MEG) and diethyl glycol

(DEG) and 25g phosphoric acid at 85% kept at 200⁰C +/- 2°C. After 10 minutes shaking (agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface and mechanically transferred to the extruder.

The fused mass was extruded at 102⁰C at 30lb/hour (30 pound/hour) through the dry spinning of 220 μm/400 holes. The obtained filaments were stored at 120°C for 5 minutes and after that were cooled at room temperature. They presented bright and light color with 450 dtex.

Picture 4 highlights the 450 dtex filaments that were obtained as example 2 describes. EXAMPLE 3

Approximately 100,0g of PAN copolymerized with 20% methyl methacrylate was added in 1000g of a mixture containing 48Og of monoethylene glycol (MEG) and diethyl glycol (DEG) and 40g phosphoric acid at 85% kept at 195°C +/- 2°C. After 10 minutes shaking (agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface and mechanically transferred to the extruder.

The fused mass was extruded at 197°C at 30lb/hour (30 pound/hour) through the dry spinning of 120 μm/ 400 holes. The obtained filaments were stored at 12O⁰C for 5 minutes and after that were cooled at room temperature. They presented bright and light color with 25 dtex. EXAMPLE 4

Approximately 100,0g of PAN copolymerized with 6% vinil acet was added to 1.00Og of a mixture containing 487, 5g of monoethylene glycol (MEG), 487,5 of glycerin and 25g of phosphoric acid at 85% kept at 190⁰C +/- 2°C. After 5 minutes shaking (agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface and mechanically transferred to the extruder.

The fused mass was extruded at 195°C at 30lb/hour (30 pound/hour) through the dry spinning of 120 μm/ 1000 holes. The obtained filaments were stored at 12O⁰C for 5 minutes and after that were cooled at room temperature. They presented bright and light color with 40 dtex.

EXAMPLE 5

Approximately 100,0g of PAN copolymerized with 6% vinil acet was added to 1.00Og of a mixture containing 495g of monoethylene glycol (MEG), 495 of glycerin and

10g of phosphoric acid at 98% kept at 19O⁰C +/- 2°C. After 5 minutes shaking

(agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface and mechanically transferred to the extruder.

The fused mass was extruded at 195°C at 30lb/hour (30 pound/hour) through the dry spinning of 120 μm/ 1000 holes. The obtained filaments were stored at 120°C for 5 minutes and after that were cooled at room temperature. They presented bright and light color with 35 dtex.

EXAMPLE 6

Approximately 100,0g of PAN copolymerized with 6% vinil acet was added to 1.00Og of a mixture containing 975g of monoethylene glycol (MEG), 25g of phosphoric acid at 85% kept at 190°C +/- 2°C. After 5 minutes shaking (agitation) the fused polymer in the form of paste, because of its lower density, is floated to the liquid surface where it can be taken out and transferred to the extruder.

The fused mass was extruded at 195⁰C at 50lb/hour (30 pound/hour) through the dry spinning with one 8mm diameter hole. The obtained wooden plug presented light yellow color with 1 ,07 g/cm² density and superficial hardness (toughness) (Rockwell M) 82. Picture 5 shows the 8mm PAN wooden plug that was obtained as example 6 describes.

Although the above description has many specificities, operational constructive variations, they must not be interpreted as a limitation to the invention's scope, but as a mere illustration of some of this invention's preferred representations to be .presented. Therefore, the invention scope must be represented by the demands here attached and its legal equivalents.

Claims

1. PROCESS of Acrylic and Modacrylic Polymer fusion, characterized by the fact of having the following steps:

(I) preparing the fusion and thermal transference means containing a high polarity non-soivent liquid;

(II) to heat the polymer's fusion temperature;

(III) to obtain a fused polymer mass;

(IV) to subject step (III) to an extrusion process;

(V) and to obtain the desired polymer's shape

2. PROCESS, according to demand 1 , characterized by the usage of a non-solvent and polar means which are stabilized with high ebullition point acids and can be employed in the manufacturing of textile and non-textile extrusion shaped objects.

3. PROCESS according to one of the demands 1 and 2, characterized by the usage high polarity substances, like glycols and their mixtures, as acrylic and modacrylic means of fusion.

4. PROCESS according to one of the demands 1 to 3, characterized by the selection of glycols among alcohols containing one or more hydroxyles per molecule and among them we can highlight the most common ones as ethylene glycol, diethyl glycol, triethylene glycol, polyethylene glycol, propylene glycol, butylene glycol and glycerol.

5. PROCESS according to one of the demands 1 to 4, characterized by the fact that diverse substances and their mixtures, if added to glycols, bar or delay the fused polymer cyclization, as, for instance, inorganic and organic acids of high ebullition point, like phosphoric acid, sulfuric acid and oxalic acid.

6. PROCESS according to one of the demands 1 to 5, characterized by applying to polymers containing a minimum 35%units deriving from acrylonitrile co-polimerized with one or more comonomers represented by acrylic units as:

(-CH₂-CH-). ^{' CN}

7. PROCESS according to one of the demands 1 to 6 characterized for having low solvent consumption.

8. PROCESS according to one of the demands 1 to 7 characterized by the fact of obtaining diverse forms for the fused polymer.

9. ACRYLIC AND MODACRYLIC POLYMER characterized by the fact of being obtained according to one of the demands 1 to 8.

10. POLYMER, according to demand 9, characterized for being fused in acrylic and modacrylic fibers

11. POLYMER, according to demand 10 characterized because extrusion molded objects are selected among tubes billet and plates.

12. ARYLIC AND MODACRYLIC POLYMER COMPOSITION, characterized for having a minimum 35% polyacrylonitrile copolymerized with other monomers.

13. ACRYLIC AND MODACRYLIC POLYMER USAGE, according to demands 9 to 12, characterized for obtaining acrylic and modacrylic fibers.

14. USAGE, according to one of the demands 13, characterized by the fact of molding diverse objects, such as tubes, billet and plates by extrusion.