WO2011047804A1 - Plastic material having increased fire resistance, method for producing same, and plastic product made of such a plastic material - Google Patents

Abstract

The invention relates to a method for producing a thermoplastic material having increased fire resistance using a biomass containing fibers, and to such a plastic material. According to the invention a biomass containing fibers is provided, the fibers are broken, at least a portion of the fibers is equipped with a flame-retardant, and the fibers are introduced in a plastic base material.

Description

 Patent application

Applicant: Biowert AG, Aarau

PLASTIC MATERIAL WITH INCREASED FIRE RESISTANCE, OF WHICH

 METHOD OF MANUFACTURING AND ARTICLE MATERIALS FROM SUCH AN ART MATERIAL

The present invention relates to a process for producing a plastic material having increased fire resistance

Plastic material with increased fire resistance and a

Plastic articles made of such a plastic material.

Plastic materials with increased fire resistance are needed in many technical fields. An example of this is the construction sector, in which plastic parts for the installation of electrical equipment, such as e.g. Flush-mounted boxes, housing of switch boxes etc.

must meet certain fire resistance requirements, so that even in the case of short circuits, a fire does not arise or can not spread. The fire resistance, which includes the plastic base material, e.g. Polyethylene or polypropylene, this offers, is usually not sufficient. To the

To increase fire resistance, flame retardants can be added to the plastic base material. Flame retardants or fire retardants are substances which limit the spread of fires and / or the development of smoke,

slow down or prevent.

In principle, four types of flame retardants are distinguished:

CONF! RMAnON CO ^ - Additive flame retardants: The fire retardants are incorporated into the flammable substances as additives

- Reactive flame retardants: The substances are themselves

 Part of the material - Inherent flame retardant: The material itself is flame retardant

- Coating: The fire retardant is applied from the outside as a coating

Flame retardants for plastics are described, for example, in DIN EN ISO 1043-4.

So far, as flame retardants to increase the

Fire resistance of plastics commonly used additives based on antimony or halogen compounds. In order to meet the respective requirements of the test standard, e.g. in the

Manufacture of flush-mounted boxes up to 25% by weight of these additives may be added prior to processing. Such additives are

comparatively expensive and significantly increase the production costs. In addition, they pose risks with regard to endangering the environment. The processing becomes more complex, since the additives before the

Processing are added to the plastic base material in a separate mixing step to be provided. Other known flame retardants which are added to the plastic are nitrogen-based flame retardants, organophosphorus flame retardants and inorganic flame retardants.

The object of the present invention is to provide a method for

To provide a plastic material with increased fire resistance and to provide such a plastic material, wherein the production is simple and inexpensive to carry out. This object is achieved by a method for producing a thermoplastic material with increased

Resistance to fire using a fiber-containing biomass, the method comprising the steps of:

- Providing the biomass containing fibers;

 - processing the fibers;

 - Equipping at least a portion of the fibers with a

 Flame retardants;

 - introducing the finished fibers into a thermoplastic

Plastic base material.

In this way, a thermoplastic plastic material can be obtained, which is easy to produce and at the same time has an increased fire resistance compared to the plastic base material. The fire resistance can be compared to the

Plastic base material without equipped fibers are significantly increased. The plastic material may be a starting product for the plastics processing industry, in particular a

Starting product for thermoplastic Umform and original form procedure. In this case, the plastic material may be formed as granules or as pellets. In the manufacture of a plastic article, the plastic material is in the form of a plastic granulate or in the form of plastic pellets of a machine, for example a

Injection molding machine, an extruder or a comparable

Machine supplied and processed into a plastic article.

The increased fire resistance is achieved by treating the fibers of the biomass and using a flame retardant

be equipped. In this way, the flame retardant can be processed very easily, since the fibers with the

Flame retardant and then these fibers in the Plastic base material are introduced. It is therefore not necessary to use flame retardant directly in the

To incorporate plastic base material. Rather, it is sufficient to equip the fibers with the flame retardant, which allows due to the chemical properties of the fibers from biomass, a different processing and the use of flame retardants that would otherwise be difficult or impossible to incorporate into plastic. However, by bringing the flame retardant with the organic fibers from the biomass, not only can the processing be facilitated. In this case, the effectiveness of the flame retardant can be increased in a surprising manner. In the described equipping the fibers with the flame retardant much less flame retardant is required than when the flame retardant directly into the

Plastic base material is introduced. In addition, the fibers contribute to improved mechanical properties of the plastic material as the fibers reinforce the plastic material. In addition, the required amount of plastic base material and thus the

Use of valuable raw materials reduced.

In order to obtain a consistently high quality, the fibers of the biomass provided are processed. For this purpose, the biomass may e.g. be treated by a macerator so that the fibers are disrupted and contained cell juice emerges. In addition, the fibers of the biomass containing cellulose, in this way of undesirable substances, such as impurities and

Proteins are cleaned. The appropriately processed fibers can then be well equipped with the flame retardant and introduced into the plastic base material.

A further improvement is achieved by providing the flame retardant in an aqueous phase. The Flame retardant may for example be suspended, dispersed or dissolved in the aqueous phase. In this way, the flame retardant can easily and evenly apply to the fibers. Therefore, a permanent connection between the fibers and the flame retardant can be achieved, which facilitates the further processing, especially since a later separation of

Flame retardants and fibers can be avoided. In particular, the finishing of the fibers can take place in an exhaust process, as it is also used in dyeing. If that

Flame retardant is present in dissolved form, the processing is particularly simple. In addition, the fibers can then be particularly easily equipped with the flame retardant, since the cellulose-containing fibers due to their hydrophilic properties

Take up water and a dissolved flame retardant easily.

Has proven particularly useful if the flame retardant contains an inorganic flame retardant and / or an organophosphorus flame retardant. As inorganic flame retardants can be used, for example: boron, boron-containing

Compounds, aluminum hydroxide, magnesium hydroxide,

Ammonium sulfate, red phosphorus, antimony trioxide, antimony pentoxide, or mixtures thereof. As the organophosphorus flame retardant, there can be used aromatic and aliphatic esters of phosphoric acid such as TCEP (tris (chloroethyl) phosphate), TCPP (tris (chloropropyl) phosphate), TDCPP

(Tris (dichloroisopropyl) phosphate), TPP (triphenyl phosphate), TEHP (tris (2-ethylhexyl) phosphate), TKP (tricresyl phosphate), ITP ("isopropylated triphenyl phosphate"), mono-, bis- and tris (isopropylphenyl) phosphates, RDP (resorcinol bis (diphenyl phosphate)), BDP (bisphenol A bis (diphenyl phosphate)) or mixtures thereof. According to the invention is particularly advantageous if the inorganic flame retardant, boron, a boron-containing compound,

especially borax and / or boric acid. These substances allow good fire protection at a low level

Smoke. They are also characterized by a good

Processability in the process according to the invention and a low environmental impact. It is particularly advantageous if the flame retardant contains boric acid and borax. According to an advantageous embodiment of the invention, it is provided that the content of boron or boron-containing compound in the finished fibers is between 1 and 10% by weight,

in particular between 2 and 7% by weight. Particularly preferred according to the invention, a content between 2.5 and 5 wt.%. A higher content of boron or the boron-containing compound leads to a higher water absorption, which can lead to a poorer quality in the thermoplastic processing.

Furthermore, it has proven useful if the plastic base material in particular contains polypropylene, polyethylene and / or polystyrene. As polystyrene, for example, styrene acrylonitrile and / or

Acrylonitrile-butadiene-styrene can be used.

A further improvement can be achieved if the fibers after processing and before introduction into the

Plastic base material to be subjected to drying.

This ensures that the introduced into the plastic base material amount of water is kept low. Nevertheless, the flame retardant remains in the fibers and can later in the

Plastic material to improve the fire resistance contribute. Particularly good properties of the plastic material are achieved when a content of dry matter of 95% is not exceeded during drying. Preferably, the fibers are dried to a dry matter content of 88 to 92%. In this case, an air-layer dryer can be used, in which the fibers are gently dried at a temperature of about 140 ° C.

Furthermore, it has proved to be advantageous if the fibers to the finish with the flame retardant to a content

Do not exceed dry matter of 90%, in particular, do not exceed a content of dry matter of 60%. As a result, a hornification of the fibers is prevented, which not only adversely affects the mechanical properties of the fibers, but also complicates the equipment with the flame retardant.

A particularly good absorption of the flame retardant is obtained when the equipment of the fibers takes place after the processing of the fibers. Good fire resistance and good processability result when the fiber-containing biomass grass clippings,

Rye grass cut, Marc and / or Bargasse contains.

The present invention also relates to a

Plastic material with increased fire resistance, containing a

Plastic base material and fibers of biomass, wherein at least a part of the fibers is equipped with a flame retardant.

Has proven particularly useful if the flame retardant contains an inorganic flame retardant and / or an organophosphorus flame retardant. As inorganic flame retardants can be used, for example: boron, boron-containing Compounds, aluminum hydroxide, magnesium hydroxide,

Ammonium sulfate, red phosphorus, antimony trioxide, antimony pentoxide, or mixtures thereof. As organophosphorus flame retardants, aromatic and aliphatic esters of phosphoric acid can be used, such as TCEP (tris (chloroethyl) phosphate), TCPP (tris (chloropropyl) phosphate), TDCPP

 (Tris (dichloroisopropyl) phosphate), TPP (triphenyl phosphate), TEHP (tris (2-ethylhexyl) phosphate), TKP (tricresyl phosphate), ITP ("isopropylated triphenyl phosphate"), mono-, bis- and tris (isopropylphenyl) phosphates, RDP (resorcinol bis (diphenyl phosphate)), BDP (bisphenol A bis (diphenyl phosphate)) or mixtures thereof.

Good fire resistance at low production costs is achieved even if the plastic base material contains, in addition to the fibers provided with the flame retardant, further fibers of biomass which are not equipped with a flame retardant.

The invention also relates to a plastic article,

prepared using the described plastic material. The plastic articles may be, for example, installation material for electrical purposes, flush-mounted boxes, surface-mounted boxes, switch housings, control boxes, pipes. The invention relates

in particular to plastic articles which are produced by means of thermoplastic production. The plastic articles can, as described above, be end products or designed as semi-finished products.

Other objects, features, advantages and applications of the present invention will become apparent from the following

Description of embodiments with reference to the drawing.

All described and / or illustrated features alone or in any combination form the subject of Invention, regardless of the summary in individual claims or their dependency.

Figure 1 illustrates schematically a method for producing a plastic material with increased fire resistance under

Use of biomass containing fibers.

In a step 1, a biomass containing fibers

provided. This may be fibers containing

Plant parts of different plants act. Particularly suitable for the method described are plant parts which are not woody and therefore contain only small amounts or no lignin. Also advantageous are plant parts that are not horny to a small extent or not at all. A cornification is added

Plant fibers usually triggered by a drying process. It is therefore proposed to use those parts of plants which have not been dried. For the method according to the invention, fresh cut grass or siled grass is particularly suitable. In this way, fiber qualities are provided as starting material whose dry substance contents are between 25 and 40% by weight. Dry matter content refers to the content of dry substance that remains when all water is removed. A content of dry matter of 25 to 40% by weight therefore corresponds to a water content of between 75 and 60% by weight. The advantage of ensiling is that the grass, which is only available at certain seasons, can be processed throughout the year without any loss of quality. Further suitable substances are rye green crop, grains and / or bar alley, although other renewable fiber-containing raw materials available depending on the region can also be used.

In a step 2, the fibers are processed from the biomass. For this example, a macerator can be used, which due to The generated friction opens the cells filled with cell fluid and lets the cell juice escape. The treatment is carried out with the addition of water, which simultaneously allows to wash out impurities and undesirable substances, so that after the

Processing the fibers are present in an open-minded and purified form. The processed fibers consist essentially of alpha-cellulose and hemi-cellulose. The ratio between these two types of cellulose depends on the time of cutting of the biomass. Both types of cellulose are also important. The alpha-cellulose is important for the mechanical stability of the fibers, the hemi-cellulose is important for the uniformity of the absorption of the flame retardant and for the processing, in particular the flowability of the plastic material in the thermoplastic processing.

In step 3, the fibers are provided with a flame retardant. In the preferred method, the equipment is provided with the flame retardant in the aqueous phase. The

Flame retardant may be provided dissolved or suspended in the water. In this way, the flame retardant is taken up in the fibers or attached to these. The equipment with the flame retardant can be done in this way just as easy as a dyeing process. As flame retardants, in particular inorganic

 Flame retardants and / or organophosphorus flame retardants can be used. Has proven particularly useful in the present process, the use of inorganic flame retardants, in particular those having boron or a boron-containing compound. A mixture of borax and boric acid has proved advantageous. These substances attract like the dye on the

processed fibers and give the fibers after the Separate the aqueous phase a lasting fire protection. The flame retardant is especially halogen-free and antimony-free and therefore harmless to the environment. It is advantageous in the inventive method, when the fibers provided in the wet state digested before the first drying with the addition of water and then with the

Flame retardants are equipped. In this way, a good absorption of the flame retardant is achieved in the fibers. On the other hand, drying before finishing would lead to cornification of the fibers. This would not only affect the mechanical properties of the fibers, but also complicates the recording with the flame retardant. After finishing the fibers with the flame retardant, the fibers are dried as intermediate step 4. This is the first drying of the fibers, which were always kept moist until then. The drying is gentle, optionally in a multi-step process. The drying can be carried out, for example, in a pad dryer at temperatures between 120 ° C and 160 ° C. The drying takes place up to a content

Dry substance of 88 to 92 wt.%, Which in other words corresponds to a residual moisture content of 8 to 12 wt.%. This gentle drying largely prevents keratinization or embrittlement of the fibers. The fibers retain their suppleness, which has a positive effect on the mechanical stability of the finished product

Plastic product. After drying, a content of flame retardant, z. B. to boron or boron-containing compound in the purified fibers between 1 and 10 wt.%, In particular between 2 and 7 wt.%, With the range of 2.5 to 5 wt.% Is particularly preferred. In a step 5, those with the flame retardant

equipped fibers introduced into a plastic base material. As plastic base material thermoplastics or components thereof can be used. Particularly suitable are polypropylene, polyethylene and polystyrene, e.g. Styrene acrylonitrile and / or

Acrylonitrile-butadiene-styrene. The introduction of the fibers into the

Plastic base material may e.g. done by compounding. According to the invention, up to 75% by weight of the fibers, all or part of which are provided with the flame retardant, can be brought together with 25% by weight of plastic base material

 (Percentages based on the fiber-containing plastic material). This will save a considerable amount of money

Plastic base material reached. Even with a share of 25% by weight of the plastic base material and 75% by weight of fibers, very good results can be achieved with regard to both strength and fire protection. It has proven useful to use the fibers in a proportion of between 25% by weight and 75% by weight. With a proportion of 40% by weight to 60% by weight fibers, very good results are achieved.

The plastic material has a content of flame retardant which is contained in or on the fibers, between 0.5 wt.% And 5 wt.%, Based on the fiber-containing plastic material.

Advantageously, the content of flame retardant is between 1% by weight and 3.5% by weight, with 1.25% by weight to 2.5% by weight being particularly preferred.

The fiber-containing plastic material may be provided, for example, in pellet or granular form, and thus further processed with conventional plastic processing machines.

Changes to these facilities are not required. The plastic material can be problematic in extrusion machines and injection molding machines are processed to a variety of plastic articles. In particular, plastic articles can be made in which increased fire resistance is important. In particular, the plastic material for plastic articles, such as installation material for electrical purposes, flush boxes, surface-mounted boxes, switch housings, switch boxes and parts thereof, pipes, etc. It can also be made of plastic articles for any other technical areas, for example for the

Vehicle construction.

How efficient an equipment of the fibers in the manner described above, the following comparative experiments. In order to achieve standard-compliant fire resistance in flush-mounted boxes made of polypropylene, a content of additives of about 25% by weight is required. These are usually antimony- and halogen-containing additives

used. Only through these extensive measures, which are also of concern to the environment, can at a

Glow wire test according to DIN EN 60695-2- 11 the required

Test temperature of 750 ° C can be achieved.

With the present invention, the same fire protection can be achieved by equipping grass fibers with only 5% by weight.

Flame retardant consisting of borax and boric acid. If one makes from these compounds with 50% by weight of fibers and 50% by weight of pure polypropylene, the borax / boric acid content based on the finished plastic material is only 2.5% by weight. Nevertheless, the glow wire test according to DIN EN 60695-2- 1 1 at a

Test temperature of 750 ° C can be achieved. This shows that the

Use of flame retardant from 25% by weight to 2.5% by weight

could be reduced. In addition, flame retardants

are used, which are much less questionable for the environment. The surprisingly good fire resistance according to the invention is also evident from the fact that flush-mounted boxes, which are commercially available

Adding fire protection additives based on boron in powder form, even with additions of 25 wt.% Of these additives do not reach the required fire protection. This proves how efficient the equipment of cellulose fibers is after the one described above

Process is especially with boron salts. In this way, the use of environmentally harmful flame retardants can be significantly reduced, as well as the costs incurred for their use. At the same time, the use of cellulose fibers, such as grass, can reduce the proportion of petroleum-based plastics by 25 to 75 percent, thereby saving additional resources and costs.

Claims

claims Process for the preparation of a thermoplastic  Increased fire resistant plastic material using biomass containing fibers, said method comprising the steps of: - Providing the biomass containing fibers; - processing the fibers; - Equipping at least a portion of the fibers with a  Flame retardants; - introducing the finished fibers into a  thermoplastic plastic base material. A method according to claim 1, characterized in that the finishing is carried out with the flame retardant in an aqueous phase. A method according to claim 1 or 2, characterized in that the flame retardant is an inorganic  Contains flame retardant and / or an organophosphorus flame retardant. 4. The method according to claim 3, characterized in that the inorganic flame retardant, boron, a boron-containing compound, esp. Borax and / or boric acid. 5. The method according to claim 4, characterized in that the content of boron or boron-containing compound in the finished fibers is between 1 wt.% And 10 wt.%, In particular between 2 wt.% And 7 wt.%. 6. The method according to any one of claims 1 to 5, characterized  in that the plastic base material contains in particular polypropylene, polyethylene and / or polystyrene. 7. The method according to any one of claims 1 to 6, characterized  characterized in that the fibers are subjected to drying after being processed and before being introduced into the plastic base material. A method according to claim 7, characterized in that during drying, a content of dry matter of 95% is not exceeded. Method according to one of claims 1 to 8, characterized  characterized in that the fibers do not exceed a content of dry matter of 90% until the equipment with the flame retardant, in particular a content of  Dry matter of 60%. Method according to one of claims 1 to 9, characterized  characterized in that the equipment of the fibers after the  Breaking up the fibers takes place. Method according to one of claims 1 to 10, characterized  characterized in that the biomass containing fibers Grass clippings, rye greens, grains and / or bargasse. Plastic material with increased fire resistance, containing a plastic base material and fibers of biomass, wherein at least a part of the fibers is equipped with a flame retardant. Plastic material according to claim 12, characterized in that the flame retardant is an inorganic  Contains flame retardant and / or an organophosphorus flame retardant. 14. Plastic material according to claim 12 or 13, characterized  in that, in addition to the fibers provided with the flame retardant, the plastic base material contains further fibers of biomass which are not mixed with a  Flame retardants are equipped. Plastic articles made using a  Plastic material according to one of claims 12 to 14.