DE1769448B2 - Process for the production of a glass fiber reinforced thermoplastic concentrate in granulate form - Google Patents

Description

20th

The present invention relates to a method of making a glass fiber reinforced thermoplastic Concentrates in granular form, whereby glass fibers are continuously passed through a thermoplastic Resin-containing container conducts and the fibers are impregnated with the resin.

Glass fiber reinforced, thermoplastic resins for injection molding have become popular in the past Years due to their superior physical properties compared to their unreinforced Counterparts enjoying growing popularity. So were z. B. brittle resins such as styrene homopolymers (crystallized or for general purposes) improved in kind and could on Areas are used that were not open to such resins until then. So z. B. the Reinforcement with glass fibers generally increases the tensile strength, it improves the impact strength both at low temperatures as well as room temperature, it improves the stiffness, reduces the cold flow and the coefficient of thermal expansion, it increases the heat resistance and improves other properties, so that these approximate the properties of some metals.

The following table shows the improvement by glass fiber reinforcement of unmodified thermoplastic Resin and compares the properties obtained with those of certain common metals.

The properties mentioned were determined as follows:

Tensile strength in kg / cm ²
Elongation in%
Tensile modulus in kg / cm ²
Izod impact strength in cmkg / cm
Deformation temperature below
Load at 18.48 kg / cm ² ; ⁰ C
Linea ^r he coefficient of
thermal expansion in
cm per cm per 0.56 ^0C

ASTM D 638-61T
ASTM D 638-6IT
ASTM D 638-6IT
ASTM D 256-56
ASTM D 648-56

ASTM D 696-44

Table 1 Nylon*) Nylon**) Poly Poly Poly Poly Metals aluminum Magne characteristic styrene *) styrene *) äthy ethylene **) sium len *) zinc 2 310- 2,380 3 290 826 2 100 525 1050 294 770 2,870 4.9 3 Tensile strength 721000 455,000 60 2.2 3.0 1.2 800 3.5 10 - - strain 31500 140,000 32 200 133,000 9 800 63,000 (crawls) - - Tensile module 5.4 18.5 2.7 11.9 10.9 21.8 - l, 2X10 " ⁵ 1,4XlO " ⁵ Impact resistant. 66 260 82 104 80 ***) 127 - Deformation. Temp. 4.5XlO " ⁵ l, 4X10 " ⁵ 4X10 " ⁵ 1.8XlO " ⁵ 6X10 " ⁵ 1.7X10 " ⁵ 1.5X10 ' ⁵ Linear coefficient

Nylon *) = unreinforced nylon 6,6.

Nylon **) = nylon 6,6 reinforced with 40% glass fiber.

Polystyrene *) = unreinforced polystyrene.

Polystyrene **) = polystyrene reinforced with 35% glass fiber.

Polyethylene *) = unreinforced polyethylene (high density).

Polyethylene **) = polyethylene reinforced with 40% glass fiber.

***) = at 4.62kg / cm ² .

As Table 1 shows, reinforcing nylon 6,6 with 40% glass fiber increased the tensile strength from 826 to 2100 kg / cm ² . While the elongation is reduced from 60% to 2.2% and the tensile modulus is increased from 17,500 kg / cm ² to 140,000 kg / cm ² , the Izod impact strength improves dramatically from 5.4 cm kg / cm for unreinforced nylon 18.4 cmkg / cm for reinforced nylon. The deformation temperature under load at 18.48 kg / cm ² is increased dramatically from 66 ° C, for unreinforced nylon to 260 ° C, for glass fiber reinforced nylon, while the linear coefficient of thermal expansion is 4.5 X10 ⁵ cm per cm is reduced in 0.56 ° C. The values of the low elongation, the high tensile modulus and the low linear coefficient of thermal expansion from the glass fiber reinforcement of thermoplastic resins give properties which are comparable to those of the three main metals used for molding, shown in the right column of the table. A similar increase in the tensile properties of polystyrene and high density polyethylene by the glass fiber reinforcement of these thermoplastics is also shown in the table.

Injection molding preparations reinforced with glass fiber of the type mentioned in the table were used in the US patent 28 77 501 described, the preparations consisting of 15-60 wt .-% glass fiber, the remainder being the resin. The properties of those mentioned in US Pat. No. 2,877,501 with glass fiber Reinforced thermoplastics have the highest values that can be found for thermoplastics reinforced with fiberglass encountered.

There are other methods besides the technology shown in the aforementioned US patent for the production of glass fiber reinforced thermoplastics. One in the industry usually called Thermoplastic resin called "short fiberglass" reinforced material can be made by one glass fiber, which has previously been cut to a length of about 6 mm, together with the Introduces thermoplastics into the hopper of a plastic extruder and mixes out

Table 2

Glass fiber and thermoplastics are genuinely extruded into strands and these strands are then assembled for the Injection molding cuts suitable tablets. The products manufactured in this way contain within the Grain dispersed glass fibers, but the fibers are usually extremely short; H. usually between 0.5-1.75 mm, although much longer glass fibers were fed into the extruder. The reduction the fiber length is caused by the very

ίο strong grinding action within the thermoplastic Tablets and the fiberglass as the mixture compresses in the extruder feed screw will. The final physical properties of these so-called "short glass" reinforced thermoplastics do not correspond to those of the materials known as "long glass" reinforced thermoplastics. These Differences are shown by comparing the physical properties in the following table

characteristic

ASTM test

Long glass
Nylon 6.6
40% glass

Short glass
Nylon 6.6
40% glass

Long glass
Polystyrene
30% glass

Short glass
Polystyrene
30% glass

Tensile strength at 23 ° C; kg / cm ²
Flexural modulus at 23 ° C; kg / cm ²
Izod impact strength at 23 ° C; cmkg / cm
Deformation temperature under load at
18.48 kg / cm ² ; ⁰ C

D 638-61T 2 100 1680 980 770 D 790-63 126,000 105,000 84,000 70000 D 256-56 18.4 7.6 13.5 2.7 D 648-56 260 249 104 99

As Table 2 shows, v> nylon reinforced with short glass has maximum tensile strengths of only 1680 kg / cm ² , while nylon reinforced with long glass has tensile strengths of 2100 kg / cm ² . The Izod impact strengths of the short glass products are also considerably lower than those of the long glass materials. So has z. B. Short glass nylon has an Izod impact strength of only 7.6 cmkg / cm, while nylon reinforced with long glass exhibits an Izod impact strength of 18.4 cmkg / cm. The difference between polystyrenes reinforced with long and short glass is even clearer. Short glass polystyrenes have an impact strength of only 2.7 cmicg / cm while polystyrenes reinforced with long glass have an impact strength of 13.5 cmkg / cm.

Since the thermoplastic resins described above, reinforced with short glass by simple extrusion, so mixing can be produced, there was a logical extension of this process for the industry. In doing so, cut fiberglass and unreinforced thermoplastic resin were put into the funnel given to an injection molding machine with a reciprocating screw. This is how the extrusion mix was created inside the screw of the injection molding machine, which is also the final shaped Partly deformed The products manufactured using this process have properties similar to those mentioned above, Thermoplastics reinforced with short glass.

There are two other similar methods of making short glass reinforced thermoplastics Resins. In one process, the pre-cut fiberglass and the non-reinforced thermoplastic material in separate streams to the funnel of the screw of an injection molding machine During the second process, a continuous fiberglass sliver directly above the Funnel of the injection molding machine and the freshly cut glass in the funnel mixed with the non-reinforced thermoplastic resin.

Both systems failed, regardless of the fiber insertion into the funnel of the deforming machine regarding sufficient dispersion of the glass fiber within the plastic resin and resulted often for the formation of fiberglass clumps and resin-enriched areas in the molded part. The education of lumps and / or resin-enriched areas leads to inconsistent and deviant physical properties within the molded piece. Lumps of fiberglass also tend to stick to to collect the surface of the molded objects and interfere with subsequent machining operations, such as Coloring, vacuum metallization or plating. When working according to the second method described above The cutting of the continuous fiberglass sliver forms large quantities of extremely fine fiberglass that floats through the air and poses problems of cleanliness and dangers to the Brings health with it.

Although the one with the unreinforced resin to the funnel of the injection molding machine, cut Glass fiber has been coated with 1 or 2% of a binder resin, the glass is practically exposed and causes when mixing with the thermoplastic, severe wear and tear on the cylinder and screw of the forming machine. This severe wear problem is adequate in the plastics industry known.

It is briefly pointed out here that from

Fiberglass manufacturers have certain binder resins applied to the fiberglass in order to facilitate the handling of the continuous fiberglass roving and its subsequent cutting to short dimensions. The choice of these binder resins is intended to facilitate handling, and often the resins come with one Thermoplastics, into which the glass fiber is then to be incorporated, incompatible. Such Incompatibility leads to poor physical properties due to the non-wetting of the glass fiber surface through the thermoplastic resin. Fiberglass manufacturers usually bring 1-2% binder resin on the surface of the glass fiber, although higher percentages are given in the literature.

In summary, it can be said that the following thermoplastics reinforced with glass fibers have been commercially available up to now available are: materials with superior physical properties, made by using long glass fibers; Short fiberglass materials made by extrusion molding; and products made by directly mixing the glass fiber and thermoplastic in the screw one Injection molding machine are manufactured.

The mixing of fiberglass and thermoplastics is immediate in an injection molding machine particularly economical, as no further treatment stages are necessary. The above, however, serious disadvantages of the direct blending method have been widely adopted by the industry prevents. Furthermore, the amount of glass fiber used in such a direct mixing process can be incorporated, severely restricted. Must for even further industrial use reinforced thermoplastics will be available at minimal cost. The economy of the direct Mixing fiberglass and thermoplastic material in the hopper of the injection molding machine would lead to such further dissemination without the disadvantages of this process. Known procedures have not shown a way that is economical with the direct mixing of glass and thermoplastics is competitive in an injection molding machine.

The direct mixing process is thus the most economical, but it has unacceptable disadvantages. the Materials of the aforementioned US patent have the best physical properties possible, however is the manufacture of a product that is economically competitive with the direct mixing process can not.

The aim of the present invention is to provide a method for producing a concentrate with a high content of long glass fiber in a thermoplastic resin that is placed in the hopper of an injection molding machine can be mixed with a non-reinforced thermoplastic. The present invention now relates to a method of manufacture a with glass fiber reinforced thermoplastic concentrate in granulate form, whereby one glass fibers continuously passes through a container containing a thermoplastic resin and the fibers with the Resin impregnated, which is characterized in that one 70-90 wt .-% glass fibers with 10-30 Gcw .- "/ o resin and impregnated with the thermoplastic impregnated glass fibers leads to a cutting zone in which they are at a temperature of at least 27 ° C to be cut into a concentrate in granulate form with a length of at least J mm.

In a particular embodiment of the present invention, the glass fibers are used in an amount of 75-85% by weight.
According to the present invention, a concentrate of long fiberglass is made which is sufficiently impregnated with a thermoplastic resin to reduce the wear and tear of an injection molding machine and which is impregnated with a "thermoplastic resin of the same kind that is used with the unreinforced thermoplastic with which it is ultimately in one The thermoplastic-impregnated concentrates of long glass fiber produced according to the invention are in the form of grains with such physical properties that they are easy to handle in the existing injection molding devices practically its entire content of long glass fibers over the entire grain length in a practically parallel direction, ie in the injection molding tablets obtained with a high concentration of glass fibers, the glass fibers are in practically para lleler direction to one of the sides (long side) of the tablet and extend practically over the entire length of the tablet.

The following terms and abbreviations have been used in the present application:

(a) Regarding thermoplastic injection molding munggranulate means "long" glass fiber one over about 3 mm in length, which practically extends over the extends the entire grain length, while a "short" glass fiber has a length of less than about 3 mm.

(b) "Multiplicity" in connection with glass fiber means that there is a large one in the glass fiber strand Number of individual fibers ("filaments") are included.

(c) "Impregnation" means the penetration of the glass fiber strand with a thermoplastic Resin so that, under optimal conditions, each individual fiberglass is coated and covered with the thermoplastic Resin is wetted.

(d) “Concentrate” is the product according to the invention. The present invention is illustrated by the drawings further illustrated.

F i g. 1 is a block flow diagram of one for performing one form of the method of the present invention suitable device.

F i g. 2 is a diagram of another device, which is suitable for carrying out another form of the method according to the invention.

In the case of the FIG. 1, the traversers shown are glass strands or rovings (actually some of these strands are used, as described in detail in US Pat. No. 3,119,718 which is hereby included in the present application) 10 from a suitable attachment gate 11 (frame) by a shown at 12! Bath led, ode in the form of a water emulsion solution of the thermoplastic resin or a

mi solution of the same in a corresponding solvent can be present, which the strand or the pre spun impregnated. The strand is then passed through an oven 13 in which the water is emulsified sion or the solvent of the solution is removed and the resin is melted. According to the As the resin passes, the impregnated strand passes near a series of heating devices 14 passed through which the temperature of the strand gc

if necessary, is raised to an appropriate temperature, whereupon it is used for tableting in the unit 15 is ready. After cutting the strand in the manner indicated, it is in the unit 16 for removal sifted of unwanted cut product and is then ready for packaging at 17. Although the above general process steps represent the process of an embodiment of the process according to the invention To illustrate, they are described in greater detail in US Pat. No. 3,119,718; these is hereby incorporated into the present application.

In the method described in FIG. 2 shown device is carried out, glass strands or roving 20 from a suitable (not shown) Slip-on gate brought up and passed through a trough 21, which is a suitable resin emulsion solution if a pre-impregnation of the strands is necessary is. As they pass through the trough, the strands or rovings are impregnated with the resin. After leaving the trough 21, the impregnated strands or rovings run through one Furnace 22 which drives off any volatile materials and melts the resin. From the Oven 22 run the strands or roving into a chamber 23, hereinafter referred to as a reservoir, containing a supply of molten thermoplastic resin. Within reservoir 23 is one Contain collecting nozzle 24, which collects the strands into a single bundle 25, which by a relative the collecting nozzle 24 aligned opening emerges from the reservoir. After cooling down accordingly, z. B. by passage through a water bath 26 to solidify the thermoplastic applied in the reservoir Resin runs through the bundle 25 between power-driven pull rollers 27, which the strands or pull roving through the device. After leaving the rollers 27, the bundle runs to one Cutting device 28, which is suitable for the formation of the desired tablets or granules Length cuts. If necessary, the impregnated strands can be arranged in a row shown at 29 be bypassed by heating devices, in which the temperature of the strand on a for Tableting in the device 28 is increased to a suitable value. While F i g. II on general Related process stages, as in the case of FIG. I, a more complete and accurate description of the Apparatus can be found in US Pat. No. 3,042,570, which is hereby incorporated into the present application is recorded. It is noted that although neither in US Pat. No. 3,119,718 nor 3,042,570 a positive heating stage is shown door the impregnated strand prior to tabletting so that the If the strand is in a condition suitable for tabletting - such a heating stage may be necessary be; it can, as shown in FIG. I shown by using lamps, e.g. B. infrared lamps or any other suitable heating source.

The shape of the strands or rovings 10 and 20 (, 0 and their number, which can be combined to form a single bundle 25, can vary widely, depending on various factors, e.g. the transverse dimensions of the finished tablets, the relative proportions of glass and resin in the finished product ^, the importance of a good contact between glass fibers and resin, ease of manufacture, etc. For many compounds form and purposes of each strand or each roving may consist of about 8-120 "chains" ( "ends") Each "chain" is made up of around 200 individual glass fibers. Where good contact between the glass fibers and the resin is important, it can be useful to reduce the number of "chains" in each strand or sliver.

The apparatus used in applying the various resins can take various forms have what i.a. on the ease of manufacture, the types of resins applied and the necessary ones Properties of the end product depends. The present invention is therefore not particularly specific Type of impregnation or coating device limited. Although a device below The use of impregnation agents of the type described above is widespread Resins can also be applied by passing the strands or rovings through liquid dispersions directs; or one can use enamel applicators. It can be useful in some cases be the resin by touch, e.g. B. by application rollers that are partially immersed in the resin bath, to raise. When using baths, the liquid impregnation and coating material can be used in be in any suitable form, e.g. B. as an emulsion of z. B. a polystyrene resin or styrene-acrylonitrile mixed polymer or as a suspension of z. B. a polyethylene resin; as a solution; as a melt of z. B. a polypropylene or polyamide resin; as a prepolymer or even as a monomer. With the latter In some cases, the bath can contain an appropriate polymerization catalyst and incorporate it be brought to the desired viscosity by finely divided polymer. The viscosity of the bath affects the amount absorbed by a strand or roving as it passes through Amount of bath material.

In a preferred embodiment of the present Invention is a process for the production of a concentrate for use in injection molding preparations created that is new. The process for making the concentrate consists of various critical stages that must be carried out accordingly to a failure to prevent. As mentioned above, the method according to the invention relates to the production of Tablets filled with tablets of unreinforced thermoplastic resin in the feed hopper of a Injection molding machine can be given to an article manufactured by injection molding with significantly superior properties compared to the unreinforced material.

Preferred is a continuous process for applying the thermoplastic resin to the Glass fiber, with roving strands through a z. B. passed a polystyrene emulsion containing container will. The strands are prior to introduction into the container with the thermoplastic resin or during of immersion in the same opened by suitable means, and that taken up by the strand The amount of resin is regulated by one of the following conditions:

(a) rate of passage of the strand through the resin (residence time of the strand in the resin);

(b) concentration of the thermoplastic in the emulsion or solution;

(c) viscosity of the thermoplastic solution, emulsion or melt; and

(d) the extent to which the excess resin is removed by any suitable mechanism, e.g. B. by passing it through of the strand is pressed through a reducing opening. So it can get through the roving The amount of resin absorbed can be controlled critically and precisely by the above variables.

After the roving has passed through the container of thermoplastic resin, it can be passed through an oven maintained at 204-37PC to remove water and / or other volatile materials and melt the resin. The particular temperature used in the oven depends on the resin used and the means of application to the fiberglass roving. When emulsions of the thermoplastic resin have been used to impregnate the fiberglass sliver, considerable heat must be applied to drive off the water in the emulsion. When using certain thermoplastic resins, especially if they have been applied from solution, the removal of the liquid and the melting of the resin can be carried out in two different stages. After the roving has passed through the thermoplastic resin solution, it can be passed through an oven maintained at a lower temperature to remove the solvent from the solvent vapors without the risk of fire or explosion. The strand is then passed through a second furnace or a zone of higher temperature in the same furnace, which is 204-371 ⁰ C jo, in order to cause the thermoplastic resin to melt on the glass fiber roving. If the glass fiber sliver is melt-coated with the thermoplastic according to FIG. II, the use of ovens for melting the thermoplastic resin on the strand is usually not necessary.

After the impregnation shown in Fig. II, the strands or rovings can from the melt impregnation zone led to a cooling zone and cooled sufficiently for handling. When using the impregnation shown in FIG the strands or rovings can be removed from the heating zone (emulsion or solution impregnation) and optionally further heated (by appropriate heating means described above) to to bring them to an appropriate cutting temperature.

It is a crucial feature of the method according to the invention that the strands or rovings made of glass fiber impregnated with thermoplastics must be cut or tabletted in order to obtain acceptable tablets above a certain minimum temperature. The minimum cutting temperature for any thermoplastic impregnated fiberglass strand is not related to the amorphous or crystalline nature of the thermoplastic on the strand, but is determined routinely during the course of the process. Usually the minimum cutting temperature has been found to be 27 "C. When _M) producing short tablets of about 3-6 mm in length, where breakage during tableting is a problem, the minimum cutting temperatures must usually be higher than for cutting longer tablets, ie from about 1.3 cm. However, the strand temperature _b 5 must not be so high as to cause the cut tablets to stick, ie the resin must not be heated to the tacky state.

Furthermore, the strand temperature must not be so high that it sticking of the strand to the pulling rollers causes. If the strand is not at the right temperature, no acceptable tablets can be produced and the product is a mass of broken fiberglass and resin. Another one, decisive feature of the granulate concentrate described here for injection molding in that the size or length of the granulate is at least about 3-6 mm, preferably 1.3 cm, must be before acceptable tablets are obtained. If the tablet length is less than about 3-6 mm, so the product breaks during tabletting, and no acceptable injection molding compound can be produced getting produced. According to the invention it is further preferred that the diameter of the granules is at least about 1.6 mm. The following examples illustrate various of the above.

The granulate concentrates according to the invention must have certain minimum physical properties to be suitable as concentrates for injection molding. They must have rigidity, i. H. the impregnated strands and the tablets obtained must be handled in the process be relatively stiff; in addition, they must have a certain "splinter" strength, which is compatible with tableting and subsequent handling of the tablets is important. These properties are in the following Examples illustrated. The injection molding granulate concentrate according to the invention must also have a certain tablets have minimum integrity, in order according to the various, in the plastics industry usual procedures to be able to be handled, such as. B. Passage through auger bit, loading from vibration hoppers, silo storage, circulation and mixing in drums, ribbon mixing, Double cone mixing and other processes in which the tablets are subjected to impact or friction forces be subjected.

Although so far in particular the use of the granulate concentrates according to the invention for injection molding mentioned, they are not limited to this; you can use unreinforced, for extrusion, Blow molding, transfer molding and compression molding suitable resins can be mixed.

The following examples illustrate the present invention without restricting it.

example 1

A number of roving glass strands with 60 chains ("ends") were as shown in FIG. 1 through a polystyrene emulsion passed, after immersion in the emulsion, strands were stripped and dried, so that 20% by weight resin remained on the remaining 80% by weight glass fiber. That wetted Sliver was passed through an oven at 260-371 "C to first drive off the emulsion water and then melt the resin around the web of glass. The resin-coated strand was made by using kept at about 65 "C by infrared heaters and at this temperature successfully turned into tablets about 1.3 cm long, cut. The glass fiber concentrate for Spritzverformu.ng was then with unreinforced polystyrene tablets mixed to form preparations with a suitable glass content range. Table 3 shows the physical properties of such blends with 0, 20 and 35% glass reinforcement.

Table 3

characteristic ASTM test 0% glass 20% glass 35% glass Tensile strenght; kg / cm ² D 638-6IT 567 840 980 Strain; % D 638-6IT 2.2 2.0 2.0 Tensile module; kg / cm ² D 638-61T 32 200 58 800 84,000 Notched Izod impact strength; cmkg / cm D 256-56 1.62 8.1 13.5 Deformation temperature D 648-56 92.8 103.3 105.6

at 18.48 kg / cm ² ; ⁰ C

Table 3 shows the suitability of the concentrates according to the invention; a similar product was found under same Conditions from a styrene-acrylonitrile latex manufactured.

Since 0.45 kg of a concentrate reinforced with 80% glass through an injection molding device with 1.36 kg of unreinforced resin mixed to form 1.81 kg of 20% glass reinforced mixture the manufacture of the concentrate reduces labor, packaging material, and apparatus by a quarter of the values required to produce 1.81 kg of a thermoplastic with 20% reinforcement are necessary. With these economic savings, a thermoplastic material can have 20% glass reinforcement can be produced at half the cost as before. The following examples show similar cost savings.

Example 2

A polypropylene resin was melted in an extruder and for immediate impregnation used according to FIG. II of a glass roving; this gave a product with about 75% glass. the Strands were successfully formed into tablets about 9.5 mm in length at a temperature of about 82 ° C cut. The tablets were then made with non-reinforced polypropylene to a total glass content mixed by 20%. After molding this mixture, the following physical properties were found obtain:

Table 4

ASTM test

the emulsion to drive off and then the polyurethane resin to melt the glass fibers. The one with resin coated strand was kept at about 65 ° C and at this temperature with success to tablets of cut about 1.3 cm in length. The glass fiber concentrate for injection molding was then unreinforced Resin mixed and molded into test specimens. There were again similarly improved properties obtain.

Example 4

First, an emulsion of high density polyethylene powder in water was made. Through this Emulsion were then passed through a series of glass roving strands with 60 chains as shown in FIG After immersion, the emulsion was wiped off and dried, leaving 20% resin on 80% by weight of glass fiber remained. The wet roving was used to drive off the emulsion water and then melting the polyethylene resin around the glass fibers through an oven at 288 ° C

Jj headed. The polyethylene resin-impregnated strand was then maintained at about 66 ^C C and cut in this Tempeiatur successfully to tablets of about 1.3 cm length. The glass fiber concentrate was then mixed with unreinforced polyethylene tablets to give a molded preparation with 20% glass; this was molded into test specimens with the following properties by injection molding:

Table 5

ASTM test

D 638-6IT 420 Tensile strenght; kg / cm D. 638-61T 455 Tensile strenght; kg / cm ² D 790-63 490 r _{) ()} flexural strength; kg / cm ² D. 790-63 560 Flexural strength; kg / cm ² D 256-56 12.4 Izod impact strength; cmkg / cm D. 256-56 10.8 Izod impact strength; cmkg / cm D 648-56 138 Deformation temperature D. 648-56 127 Deformation temperature at 18.48 kg / cm ² ; "C at 18.48 kg / cm ² ; ⁰ C «Example 5

These data were obtained using a conventional polypropylene homopolymer; it however, polypropylene copolymers can also be used.

Example 3

A series of glass roving strands with 60 chains were passed through a conventional polyurethane emulsion as shown in FIG directed. After immersion, the emulsion was stripped off and the glass roving opened a resin content of 20% with 80% by weight glass fiber. The wet roving was through a Oven of about 26O "C passed to first the water It was a solution of polystyrene resin for general Purposes made in toluene as a solvent containing about 5% polystyrene. According to W) Fig. I made a series of roving glass strands passed through this solution with 60 chains. After immersion, the solution was wiped off and the Strands dried to a content of 25% resin on 75% by weight glass fiber. The wet roving was to drive the toluene out of the solution and then melt the polystyrene to the Glass fibers passed through an oven at 204 "C. The polystyrene-impregnated strand was reduced to about

Maintained 66 ° C and cut successfully at this temperature into tablets of about 1.3 cm in length. That Glass fiber concentrate was then combined with unreinforced polystyrene tablets to form a molded preparation with 20% Glass mixed by injection molding into test specimens with properties similar to those in Table 2 for 20% glass fiber was shown to be deformed.

As mentioned above, the concentrate tablet must be at a certain elevated temperature, that of the resin to be varied to resin, cut; this is necessary to achieve the results according to the invention. So is z. B. for polystyrene a suitable cutting or tableting temperature at about 27-77 ° C, preferably 38-71 ° C. The same temperature range applies to concentrates made from styrene / acrylonitrile copolymers (SAN). At the specified Temperatures, the tableting takes place satisfactorily and with an acceptable minimum number chipped and broken tablets. Although the precise indication of a suitable temperature for everyone thermoplastic resins are difficult, they are generally above about 27 ° C, preferably above 32 ° C, but below the temperature at which the cut tablet becomes sticky to the Tends to agglomerate. Other suitable temperatures are for:

Polyethylene

Polypropylene

Polystyrene

32-60 ⁰ C
38-71X
38-71 ° C

Although the physical properties of the concentrates themselves - in strand or tablet form usually would not be determined since the ultimate primary purpose of these concentrates is in mixing with non-reinforced resins, the following were used to characterize these concentrates Properties determined. In the following Table 6, the Izod impact strength became one with polystyrene impregnated single strand of 60 glass fiber chains determined according to ASTM method D-256-56. The sample holder has been modified to accommodate a single strand sample. With a varied glass content of the Strands, the Izod impact strength increased rapidly and then decreased as the glass content approached 100%.

Table 6

% Glass izod impact strength;

cm kg / cm

0 13th 30th 108 80 70.2 90 21.6 100 0

As mentioned, the tablets according to the invention must have a certain minimum splinter resistance for handling in conventional injection molding devices. Furthermore, the impregnated strand produced according to the invention must have sufficient splinter resistance which is suitable for tableting. According to a test determined for this purpose, the shatter resistance of a tablet is preferably around 7 kg / cm ² . It was determined for a tablet by adding the

ίο measured strength that was necessary to a common ¹ -; Embroidery sewing needle No. 1 through the diameter of a tablet at a speed of 2.5 mm / min. The force was measured on a standard Instron tester; the value was divided by the cross-sectional area of the tablet to bring the values on the same basis. For this purpose, tablets impregnated with polystyrene were used. All of the glass-containing samples, as expected, splintered due to the oriented fibers along the length of the tablet. A tablet made of unreinforced polystyrene (0% glass) splintered perpendicular to the length at the puncture point, as was to be expected due to the lack of glass; the splintering was in the weakest direction. All of the values given below are the average of around 15 individual determinations.

Table 7 Splinter resistance % Glass kg / cm 486 0 288 30th 162 80 32.4 90 0 100

For the production of the improved preparations according to the invention, the various decisive factors must therefore be used Factors are met, each of which contributes to the overall success of the invention.

As can be seen from the above examples, any thermoplastic resin can be used in the present invention become, such as B. polystyrene, acrylic resins, styrene-acrylonitrile copolymers, Acrylonitrile / butadiene-styrene resins (ABS resins), polyvinyl chloride resins, polyformaldehyde resins, Polysulfone resins, polyphenylene oxide resins, polyamide resins such as nylon, polyester resins, Polyolefin resins such as B. polyethylene or polypropylene resins, polycarbonate resins, etc.

The rovings or strands of glass used in the present invention can be made with many commercially available Sizing agents such as polyesters, polyvinyl acetates and / or coupling agents from the silane or

Chromium complex type, be coated.

1 sheet of drawings

Claims (1)

Claim; Process for the production of a thermoplastic concentrate reinforced with glass fibers in granular form, wherein glass fibers are continuously passed through a container containing a thermoplastic resin and the fibers are impregnated with the resin, characterized in that 70-90% by weight of glass fibers with! 0-30 Wt .-% resin impregnated and the glass fibers impregnated with the thermoplastic leads to a cutting zone in which they are cut at a temperature of at least 27 ⁰ C to a concentrate in granulate form with a length of at least 3 mm.