WO2009074876A2

WO2009074876A2 - Wound glass fiber-reinforced plastic pipes, and method for the production thereof

Info

Publication number: WO2009074876A2
Application number: PCT/IB2008/003769
Authority: WO
Inventors: Carlström BENGT
Original assignee: Caldero Trust Reg
Priority date: 2007-12-11
Filing date: 2008-12-11
Publication date: 2009-06-18
Also published as: WO2009074876A3; DE102007059817A1

Abstract

The invention relates to a wound glass fiber-reinforced plastic pipe which has a multilayer structure and comprises a core layer. Said core layer is formed from at least one polyester resin mixture, sand, glass fibers, and optional additives. The polyester resin mixture is a mixture of a polyester resin, a filler, and optional additives.

Description

description

Wound glass fiber reinforced plastic tube and process for its production

The invention relates to wound glass fiber reinforced plastic pipes and a process for their preparation.

Glass fiber reinforced plastic (GRP) pipes are generally made in the prior art either by the Drostholm process or by the centrifugal process. In the Drostholm process, thin-walled, narrow steel blades are wound in a spiral on a core. The steel sheets are displaced along the core by the action of a device disposed obliquely to the core. On the thin steel core thus formed, glass fibers and polyester resins are applied.

The schematic structure of plastic tubes obtained by means of the Drostholm method or further developments of this method is shown in FIGS. 1 and 2. The individual layers are numbered, wherein the layer which forms the outside of the tube, each marked with the numeral 1 and the following layers are denoted by numbers which increase in the direction of the tube axis, so that the layer forming the tube inside has the highest digit. The layers are formed from one or more polyester resins, wherein each layer is added depending on their function, different additives such as sand, glass fibers, nonwovens and optionally additives. In Figs. 1 and 2, the layers are substantially characterized by the indication of the polyester resin added additives ^¬ .

The GRP pipe shown in FIG. 1 has the following layers from the outside of the pipe to the inside of the pipe:

(1) an outer polyester resin layer with roving in the circumferential direction;

(2) a sand layer (3) an inner polyester resin layer with roving in the circumferential direction; and (4) a roving fabric.

The GRP pipe shown in FIG. 2 has the following layers from the outside of the pipe to the inside of the pipe:

(1) an outer cover layer serving as a protective layer, for example, a nonwoven surface mat embedded in a polyester resin;

(2) outer polyester resin layer (roving layer) in which the glass fibers are circumferentially oriented;

(3) a core layer comprising sand-filled polyester resin and roving;

(4) an inner polyester resin layer (roving layer) in which the glass fibers are circumferentially oriented; (5) a barrier with short roving; and

(6) An inner cover layer formed by a nonwoven fabric.

The layers denoted by (2) and (4) in Fig. 2 are also referred to functionally as structural layers, layer (2) being the outer structural layer, while layer (4) being the inner structural layer. By means of the Drostholm process GRP pipes are obtained, which have a continuous roving, wherein in addition an axial reinforcement can be provided. The continuous roving extends over the entire length of the tube. In contrast, cut glass fibers are used in the centrifugal process to obtain spun fiberglass tubes. Sliced glass fibers used in the centrifugal process offer the advantage of preventing leakage of the produced GRP pipe. For pipes manufactured using the Drostholm process, it has been difficult for a long time to produce pipes without defects.

Due to the different manufacturing techniques and the resulting different rovings, insights pertaining to the production of hurled pipes can not easily be transferred to the production of wound pipes. In the known wound GRP pipes, no fillers other than sand have been used for this reason. However, the fillers used to make spun fiberglass pipes have resulted in a cost reduction because the polyester resin used is more expensive than the filler.

The object of the invention is to eliminate the disadvantages of the prior art. In particular, a wound glass-fiber-reinforced plastic tube is to be specified, which can be produced more cheaply while maintaining the same quality. This object is achieved by the features of claims 1 and 6. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 5 and 12 to 16.

According to the invention, a wound glass fiber reinforced plastic tube is provided, which is constructed of a multilayer and comprises a core layer, which is formed from at least one polyester resin mixture, sand, glass fibers and optionally additives, wherein the polyester resin mixture is a mixture of a polyester resin, a Filler and optionally additives. A preferred filler is calcium carbonate.

The glass fibers contained in the core layer are present in the circumferential direction as a ring. In addition to the roving in the circumferential direction, the core layer may also include short rovings.

The use according to the invention of a filler in the core layer makes possible an approximately 30% reduction in the proportion by weight of the polyester resin, which is associated with a considerable cost advantage. Further, due to the use of the filler, a higher modulus of elasticity of the core layer can be achieved, allowing a reduction in the wall thickness of the tube. Moreover, the inventive tubes further allow a nominal diameter of 4 m.

The term "core layer" is to be understood as meaning a layer of the plastic tube which lies between two layers, and thus the plastic tube according to the invention comprises at least three layers.

The expression "polyester resin mixture" is to be understood as meaning a mixture which comprises at least one polyester resin and one filler fabric includes. The filler can be any filler except sand. The polyester resin mixture may contain more than one filler. It may also have various polyester resins. Moreover, the polyester resin mixture may contain additives. The proportion of these additives to the polyester resin mixture preferably exceeds 20 wt .-%, based on the weight of the polyester resin mixture is not.

In a preferred embodiment, no more than 2% by weight of the filler, based on the weight of the filler in the polyester resin mixture, should have a grain size exceeding the diameter of the glass fibers. If the core layer also contains short rovings in addition to the roving, the diameter of the glass fibers forming the roving in the circumferential direction is decisive.

If the proportion by weight exceeds 2% by weight, cracks may occur in the polyester matrix. In Fig. 5 is shown schematically that the total elongation in the length d must be taken up by the part of the bars a and b, since the filler K can not absorb any stretch over its length b.

Preferably, the proportion of very small grains of the FuIl- substance, d. h is grains having a size less than 1 μm, at most 10% by weight, based on the weight of the filler in the polyester resin mixture. This proportion of very small grains of filler delays the separation of the larger grains. Furthermore, far the filler preferably has a specific surface area of 1 m ² / g. The elongation at break of the polyester resin used of the polyester resin mixture is at least 2%, preferably 2 to 3%, particularly preferably 2.5%.

In the polyester resin mixture, the polyester resin should be present in a ratio of 1: 0.5 to 1: 2, preferably 1: 1.5, each by weight, to the filler.

Additives which may be added to the polyester resin mixture include catalysts such as acetone-acetyl peroxide (AAP) and tert. Butyl perbenzoate (TBPB); Inhibitors such as butylcatechol; Accelerators such as N, N-diethylacetoacetamide, cobalt octate and cobalt naphthanate; and viscosity reducers such as BYK.

The additives provided in the core layer are preferably mixed completely with the polyester resin mixture according to the invention during its production. Alternatively, however, the additives may instead be completely supplied to the tube winding systems during the application of the polyester resin mixture according to the invention. Likewise, some of the additives may be added to the polyester resin mixture during its production and another part fed during the application of the polyester resin mixture according to the invention to the tube winding system.

The polyester resin used for the polyester resin mixture of the present invention may be, for example, an unsaturated polyester resin such as e.g. B. Polymal ^® 104 or 204.

The term "roving" is understood to mean bundles of endless, untwisted, stretched glass fibers, the glass fibers preferably having a diameter of 11 to 17 μm. Roving in the circumferential direction thus involves endless glass fibers which are introduced in the circumferential direction into the layer, preferably by means of a winding machine.

The term "short roving" is understood to mean comparatively short pieces of glass fibers, short rovings generally have a length of 25 to 75 mm, and short rovings represent a further reinforcement in order to increase the elongation at break of the fiberglass tube. Layers (structural layers), the core layer and the barrier layer may be provided.

The polyester resin mixture can be used in addition to the core layer for other layers of the GRP pipe, wherein the composition and properties of the polyester resin mixture in each layer, including the core layer can differ. However, if the polyester resin mixture according to the invention is used for further layers, it is expedient to use the same polyester resin mixture for all these layers in order to simplify the tube production process.

For layers for the production of which no polyester resin mixture is used, it is possible to use polyester resins which differ from the polyester resin which was used for the preparation of the polyester resin mixture according to the invention. However, the same polyester resin can be used for these layers as for the polyester resin mixture.

The choice of polyester resin is determined by the desired properties of the particular layer. For the inner one For example, a cover layer forming the inside of the pipe should be made of a polyester resin having an elongation at break of 3 to 4% in order to ensure the tightness of the pipe under an internal pressure load.

In one embodiment of the plastic tube according to the invention, the following layers are provided starting from the outside of the tube to the inside of the tube:

(a) an outer cover layer; (b) an outer roving layer with roving in the circumferential direction and short rovings;

(c) the core layer;

(d) an inner roving layer with roving in the circumferential direction and short rovings; (e) a barrier with short roving; and (f) an inner cover layer.

The outer cover layer is also called a protective layer. The barrier layer preferably contains glass fibers in the form of short rovings.

The polyester resin mixture according to the invention may be used in addition to the production of the core layer for the production of at least one of the layers (a), (b) and (d), wherein - as stated above - the composition and properties of the polyester resin mixture in each layer , including the core layer can differ. For the preparation of the layers (e) and (f) is preferably a polyester resin, but not the inventive polyester resin mixture used. According to the invention a process for the preparation ^¬ position of the inventive wound glass-fiber reinforced plastic pipe is further provided with a multilayer structure, to which a pipe winding plant applied to the layers of the plastic pipe one by one, is used. Such a tube winding system is described for example in US 4,011,354. The method comprises:

(a) providing a polyester resin and a filler in a weight ratio of the polyester resin to

Filler of 1: 0.5 to 1: 2;

(b) introducing the polyester resin, the filler and optionally additives into a mixing device;

(c) mixing the polyester resin, the filler and optional additives in the mixer to obtain a polyester resin mixture; and

(d) applying the polyester resin mixture obtained in step (c) to the tube winding system, wherein the tube winding system during the order of the polyester resin mixture can simultaneously sand and / or glass fibers, which are required to form the respective layer, nen fed ,

The layers are successively applied to the tube winding system, wherein the layer, the layer which is to form the tube inside of the tube to be produced (inner cover layer), is begun and then the respectively following layer is applied to the outer cover layer. The layers are formed by adding a given poly- ester or, if the inventive polyester resin mixture is used for the construction of the respective layer, the polyester resin mixture are applied to the tube winding system. During the application of the polyester resin or the inventive polyester resin mixture, the other constituents of the layer to be produced are likewise applied to the tube winding system. If a roving in the circumferential direction is provided in the layer, the roving is wound around the tube winding system during the application of the polyester resin or the polyester resin mixture according to the invention and the other constituents in the circumferential direction. The application of the polyester resin or the polyester resin mixture and the other components except for the circumferential roving is expediently carried out by requiring them from the top of the tube winding system.

After applying all layers, the tube is hardened, for example, by exposure to heat, such as infrared radiation or induction heat, and then optionally cut to size.

To prepare the polyester resin mixture according to the invention (step c), a turbine mixer is preferably used. The turbine mixer should be operated at a speed of 1000 to 2000 revolutions / min.

A turbine mixer consists essentially of a small disc located in a mixing container, which is operated at very high speeds. On at least one side of the disc there are traces which cause a circulation flow of the mixed material. The speed depends on the Diameter of the disc, but should be in the order of 1000 to 2000 revolutions / min. The diameter of the disc should be 30 to 50% of the diameter of the mixing container.

Conveniently, step (c) is performed under vacuum to remove trapped airborne particles.

The invention will be explained below with reference to the drawings. Show

Fig. 1 is a schematic representation of the layer structure of a first GRP pipe according to the prior art;

2 shows a schematic representation of the layer structure of a second GRP pipe according to the prior art;

Fig. 3 is a schematic representation of the layer structure of a first embodiment of the invention

FRP pipe;

4 shows a schematic illustration to illustrate the required particle size distribution; and

Fig. 5 is a schematic representation of the layer structure of a second embodiment of the inventive GRP pipe.

Claims

EXAMPLES FIG. 3 shows the construction of a first embodiment of the wound glass fiber reinforced plastic pipe according to the invention. The tube comprises the following layers: (a) an outer cover layer (# 1); (b) an outer roving layer with circumferential roving and short rovings (# 2); (c) the core layer (# 3), (d) an inner roving layer with circumferential roving and short rovings (# 4), (e) a short roving barrier (# 5); and (f) an inner capping layer (# 6). For the preparation of the polyester resin mixture of the present invention used for the core layer, calcium carbonate having an average grain diameter of 2.5 microns was used, with only 2 wt% of a grain - Have diameter over 15 microns. The polyester resin has an elongation at break of 2.5%. The tube shown in Fig. 3 had a nominal diameter of 1000 mm (DN 1000) and a nominal stiffness of 5000 N / m 2 (SN 5000). Table 1 shows the layer thicknesses and the composition of Layers indicated. Table 1 layer no. Wall Thickness Composition1 0.25 mm 1.14 kg Polyester resin mixture3.5 m2 Nonwoven2 0.85 mm 2.45 kg Polyester resin mixture 4.1 kg Roving in circumferential direction and short roving3 12, 5 mm 34 kg Polyester resin mixture6, 8 kg Roving in Circumferential direction and short rovings60 kg sand4 1,2 mm 3,1 kg polyester resin mixture5,3 kg Roving in circumferential direction and short rovings5 1,2 mm 3,45 kg polyester resin2,3 kg short roving6 0, 25 mm 0.9 kg polyester resin3,5 m2 nonwovenThe material for the Core layer (layer No. 3) polyester mixture used according to the invention was a mixture of 100 parts of polyester resin (Polymal® 204 from Organika-Sarzyna Company, PL) and 150 parts of calcium carbonate (for example Omycarb® 15 -VA from Väpennä, CZ). The polyester resin mixture thus contained only 13.6 kg of polyester resin. In contrast, for a conventional core layer of a pipe as shown in Fig. 2, 19 kg of polyester resin had to be used. This means a reduction of pure resin consumption by 28%. The polyester resin mixture which was used for the core layer (3) was also used for the layers (1), (2) and (4). Moreover, the modulus of elasticity of the core layer of the pipe according to the invention is about 20% higher than at Prior art pipes, so that the wall thickness of the FRP pipe according to the invention could also be reduced. The second embodiment of the FRP pipe according to the invention shown in FIG. 5 corresponds to the first embodiment shown in FIG. 3, except that the core layer also includes short roving. Furthermore, the outer cover layer has a fleece. claims

1. A process for producing a wound glass fiber reinforced plastic pipe having a multilayer structure and a core layer, which is formed from at least one polyester resin mixture, sand, glass fibers and optionally additives, wherein the polyester resin mixture is a mixture of a polyester resin, a filler and given if there are additives, and wherein at least part of the glass fibers are wound continuous fibers oriented in the circumferential direction of the tube, using a tube winding system to which layers of the plastic tube are successively applied

(a) providing a polyester resin and a filler in a weight ratio of the polyester resin to the filler of 1: 0.5 to 1: 2;

(d) the application of the polyester-resin mixture obtained in step (c) to the tube winding installation, the tube winding installation simultaneously applying sand and / or glass during the application of the polyester resin mixture. fibers, which are required to form the respective layer, can be supplied.

2. The method according to claim 1, characterized in that step (c) is carried out in a turbine mixer under vacuum and at a rotational speed of 1000 to 2000 revolutions / min.

3. The method according to claim 1 or claim 2, character- ized in that step (c) is carried out in a turbine mixer containing a rotating disk whose diameter amounts to 30 to 50% of the diameter of the Mischbe- beters.

4. The method according to any one of the preceding claims, characterized in that it further comprises the step

(e) curing the pipe by exposing it to heat

includes.

5. The method according to claim 14, characterized in that the tube in step (e) is carried out by means of infrared radiation or induction heat.

6. A wound glass-fiber reinforced plastic tube which has a multilayer structure and comprises a core layer, characterized in that the core layer is formed from at least one polyester resin mixture, sand, glass fibers and, if appropriate, additives, the polyester resin mixture being a mixture of a polyester resin, a filler and optionally additives, and wherein least one part of the glass fibers wound endless fibers are oriented in the circumferential direction of the tube.

7. plastic tube according to claim 6, characterized in that the filler is calcium carbonate.

8. plastic tube according to claim 6 or claim 7, characterized in that at least in one of the layers, a fleece is embedded.

9. plastic tube according to any one of claims 6 to 8, characterized in that no more than 2 wt .-% of the filler, based on the weight of the filler in the polyester resin mixture, have a grain size which exceeds the diameter of the glass fibers.

10. plastic tube according to one of claims 6 to 9, characterized in that the breaking elongation of the polyester resin, which was used for the preparation of the polyester resin mixture amounts to at least 2%.

11. Plastic tube according to one of claims 6 to 10, characterized in that the elongation at break of the polyester resin, which was used for the preparation of the polyester resin mixture amounts to at least 2.5%.

12. Plastic tube according to one of claims 16 to 11, characterized in that the cover layer, which forms the tube inside, has an elongation at break of at least 3%.

13. Plastic pipe according to one of claims 6 to 12, characterized in that in the polyester resin mixture, the polyester resin in the ratio 1: 0.5 to 1: 2, based on the weight, is present to the filler.

14. Plastic tube according to one of claims 6 to 13, characterized in that in the polyester resin mixture, the polyester resin in a ratio of 1: 1.5, based on the weight, is present to the filler.

15. Plastic tube according to one of claims 7 to 14, characterized in that the plastic tube, starting from the tube outside to the inside of the tube, comprises the following layers: (a) an outer cover layer;

(b) an outer roving layer with circumferential roving and short roving;

(c) the core layer;

(d) an inner roving layer with roving in the circumferential direction and short roving;

(e) a barrier with short roving; and

(f) an inner cover layer.

16. Plastic tube according to claim 15, characterized in that for the production of at least one of the layers (a),

(b) and (d) a polyester resin mixture corresponding to that of the core layer was used.