DE4133421A1 - Carrying panel of pallet comprises planks fixed to blocks - moulded from mixt. of fibres or stalks having layer of wax on surface and heat-hardening unsatd. polyester resin as binder - Google Patents

Abstract

In the pallet (I) consisting of carrying panel formed from several planks (2, 3) and several blocks (1) applied on their undersides, sepd. from each other, as feet, the blocks are moulded out of mixt. (4) of : (A) heat-hardening unsatd. polyester resin (II) as binder, and (B) fibres or stalks having their layer of wax on their outer surfaces, the wax being bonded on the surface with (II). ADVANTAGE - (I) have improved mechanical strength and abrasion resistance compared with pallets made using blocks mfd. from sawdust or wood shavings and adhesive, waste prods., cheaply in large amts., are used.

Description

The invention relates to a range, best consisting of one of several boards Support plate and several, on the underside blocks placed at a distance from each other as feet zen, the blocks from a thermal curing binder and individual components standing mixture are pressed.

Pallets are suitable for charge formation and er facilitating transshipment during transport, because they are driven under, lifted and lift conveyors can be transported. They usually have an Support plate formed from boards, at the Un spacing from the floor surface and providing one of the fork of the för derfahrzeuges reachable space with feet ver are seen. As a rule, the feet are in the corners and nodes of the support plate educational boards, which are usually at the front prevailing square arrangement and others, boards nine arranged in the perpendiculars Number of feet. For further improvement stability can sometimes affect the feet on the bo the end face over boards with each other be connected.  

Wood is used as the material time blocks are used because of this are made that sawdust or sawdust with mixed with an adhesive and pressed. How not If a more detailed explanation is required, the generally produced in standardized sizes Lathe highest mechanical during use Loads so that their quality in decide the degree of pressure resistance, abrasion stability and break resistance is determined. Here proves to be a decisive disadvantage that at the use of sawdust or shavings Abrasion resistance not to the required extent ben and the lifespan of the pallet essentially determine.

Proceeding from this, the invention has the Wei Development of such pallets to Task made that the mechanical strength and Resistance to abrasion is improved.

According to the invention, this object is achieved by that the individual components are fibers or straws, which has a wax layer on its surface sen that the binder is an unsaturated poly is ester resin and that the wax with the polyester Resin forms a bond on the surface.

One of the key ideas of the present invention be it says instead of sawdust or shavings long fibers or stalks that interlock grab, cross-linked with each other via the binder be and here the breaking strength essential  Lich increasing net-like structure. Here is the term fibers or straws in the sense of the Er to be interpreted broadly and includes elongated ge form with a certain elasticity due to the Need to have a wax on the surface have layer, usually vegetable original are jump because nature protects against outside Actions and for guiding and guiding the plant Zen and cell fluids superficially one Wax layer forms.

The use of fibers or straws is available knew experience against that, even under use Use of adhesives as binders after finishing achieved no dimensional stability during the pressing process can be and the fibers or straws strive are in their starting position, d. H. in a state return to lower density. Is supported this endeavor through the superficial wax layer because they have close contact between fibers or straws and binders difficult or even völ lig prevents.

To solve this problem and to preserve it digender pressing results is the invention in proposed another key feature gene, an unsaturated polyester resin as a bandage medium to use and compress that wax of fiber or straw superficially with the poly ester resin forms a bond. For this is required derlich that during the pressing process Pressed material to a certain narrow temperature warmed richly. Finds at lower temperatures  no bond between wax and polyester resin instead and at higher temperatures occur in more or less high charring on fibers or Culms up. Both influences result in disadvantage Way to reduce the mechanical Fe consistency. The one on the surface has a similar effect wax layer of fiber or stalk, the the elasticity and breaking strength and also the Resistance to moisture and vegetable and animal pests improved.

From the use of fibers or straws and their Networking with each other and the intimate connection dung to polyester resin, which by their unsaturated supported character and encouraged, results a significant increase in breakage and Compressive strength of the blocks and consequently the pallet ten as well as a stability of the form and a Fe resistance to abrasion. The material is still impact-resistant and screw-proof and can be done with übli Easily and easily process chem tools. The Material is due to the presence of the wax layer more resistant to chemicals and moisture and resistant to plant and animal Pests. Sound and heat insulation is basic very high and can be adjusted affect the bulk density. Electrostatic charging there are no endings. In the result you get a range that is characterized by high mechanical loading resilience and abrasion resistance at the same time easy processing and resistance to distinguishes external influences. The invention Pallet turns out to be from the stand  the technology is therefore known to be far superior gene.

In an expedient embodiment is pre beat as natural fibers or stalks Use straw. As a waste product it is in large quantities available inexpensively an outer wax layer and has a high, through the trapped air causes temperature i solvency, so that a transfer of Heat or cold from the stand area to the Good located largely under the support plate remains. The straw should be left natural not to affect the wax surface or to destroy.

The strength of the block can be determined in certain Limits influenced by changing the resin content rivers. This improves the strength of egg ner increase in the proportion of resin. Best results is kept at a polyester resin content of 10 to 40 weight percent.

The density of the block, which is influenced and adjusted by the pressures exerted during the pressing process, should be at least 580 kg / m ³ . A high density also increases the strength here.

As already mentioned, creating a ver bond between wax and surrounding polyester resin a certain temperature that triggers the reaction  required, usually without additional heating and other aids during the pressing process trains. The time until hardening will be agrees with the size of the block and can larger dimensions sometimes a lot of time say so that an economically justifiable Production pace is not feasible. Here emp there is little, if any, addition of Harder, through which the setting of the polyester resin and consequently also the work cycle essential can be accelerated.

The following is a process for making the described range of the invention.

First, the blocks are made in that a mixture of fibers or straws attached to their Surface have a layer of wax, with uneven saturated polyester resin and then mixed be pressed at such a temperature that the wax superficially with the polyester resin connects. At the same time, make sure that the temperature does not exceed that value, where the fibers or stalks begin to carbonize nen. At the end of the curing process one the finished block, on which one is in itself sick way the boards forming the support plate (and possibly additional ones on the sub side) attaches and fastens.  

Practical studies have shown that results are favorable, that is, the density of the starting product and the development of an advantageous temperature of the material to be pressed are at a pressure of 80 to 700 kp / cm ² .

To create a connection between polyester Resin and wax without damaging fibers and straws conditions are recommended where pass in the material to be pressed during the pressing process entering a temperature of about 72 ° Celsius poses.

Finally, a device for through leadership proposed this procedure in which it a well-known hydraulic press acts, with the proviso, however, that the material to be pressed surrounded by hot plates, between which the stem pel engages during the pressing process. Sense and The purpose of the heating plates is the possibility the optimal temperature during the pressing process to be set independently of the respective pressure.

Further details, features and advantages of the Er can be found in the following description Take part of the exercise in the drawing an embodiment of the invention in schematic sher representation is explained in more detail. Show it:  

Fig. 1 shows a cross section through a pallet,

Fig. 2 shows a fiber in cross-sectional view and in enlarged representation,

Fig. 3 is a side view of a suitable for implementation of the manufacturing process th press.

Fig. 1 shows in principle representation a range, three blocks ( 1 ) and a plate belonging to the support plate ( 2 ) and on the underside another of the additional stabilization board ( 3 ) are shown. The range shown differs from those known from the prior art in that the blocks consist of a highly unbreakable and pressure-resistant material. It is formed from individual fibers ( 4 ), which are arranged in a dense arrangement and mutually overlapping and interlocking, so that the result is a network that gives the block ( 1 ) a higher strength in the manner of a reinforcement.

In Fig. 2, a fiber ( 4 ) is shown in an enlarged cross-sectional view, so that the wax layer ( 5 ) located on the outer surface can be easily recognized. A further improvement in the stability results from the use of an un-saturated polyester resin which connects to the surface of the wax layer ( 5 ).

Fig. 3 shows a side view of a press which is particularly suitable for carrying out the method according to the invention. In order to generate the desired pressure, the punch ( 7 ) guided in the press frame ( 6 ) is moved via a hydraulic cylinder ( 8 ), the hydraulic medium being conveyed via a pump ( 9 ). The features described so far are common to hydraulic presses.

The difference compared to the prior art is that on the press table ( 10 ) verti cal aligned heating plates ( 11 ) are arranged, between which the material to be pressed ( 12 ) is to be introduced. Inside the heating plate there are heating rods ( 13 ), which are set via a temperature controller ( 14 ) so that the optimum temperature for achieving the best possible product quality is set during the pressing process.

The invention is not on the range and that Process and the device for its production limited. It extends in general the creation of a formable and hardenable material, whose starting and base material is organic and / or natural fibers, especially straws, Straw or other fibrous plants.  

Cold hardening systems

The most important cold hardening systems are organic Cobalt salts in combination with ketone peroxides based on methyl ethyl kentone, cyclohexanone and acetylacetone and others Benzoyl peroxide in combination with dimethaniline, diethylaniline or dimethyl-p-toluidine.

The cobalt hardening is almost universally applicable. The weak points are only the strong extension of the hardening times at low temperatures and the very short shelf life of kentone peroxide-containing resin mixtures.

Amine hardening offers a particularly fast initial hardness, that is, a favorable ratio between gel time and Ent molding time. Weak points are the clear surface stickiness in a thin layer, the very strong discoloration of the finished parts all under the influence, the aging, as well as the worse Degree of curing.

The heat hardening, hardening without accelerator is also called Heat curing because temperatures above 50 ° C (mostly 120-160 ° C) are required to within a short time to achieve a good degree of curing. Above about 100 ° C accelerators are generally superfluous or even harmful.

The speed of hardening is hardly increased, the bearings ability of the activated, accelerator-containing resin formulation on the other hand, significantly impaired. Especially the shelf life However, over several months is a particularly important requirement on molding compounds and resin mats. Only such are therefore suitable Hardening systems that are both thermally and chemically sufficient are stable.

Claims (11)

1. Pallet consisting of a support plate formed by several boards and several, on the underside of which are spaced apart as feet on blocks, the blocks being pressed from a mixture of a thermosetting binder and individual components, existing mixture, characterized in that the individual components are fibers ( 4 ) or straws, which have a wax layer ( 5 ) on their surface, that the binder is an unsaturated polyester resin and that the wax has a surface bond with the polyester resin. 2. Pallet according to claim 1, characterized characterized that the individual components are natural straws. 3. Pallet according to claim 1 or 2, marked characterized by a polyester Resin content from 10 to 40 percent by weight. 4. Pallet according to one of claims 1 to 3, characterized by a density of the block ( 1 ) of at least 580 kg / m ³ . 5. Pallet according to one of claims 1 to 4, ge characterized by a ge rings addition to hardener. 6. A process for producing a pallet according to egg nem of claims 1 to 5, characterized in that a mixture of fibers ( 4 ) or straws, which have a wax layer ( 5 ) on their surface, mixed with unsaturated polyester resin and then in one Temperature is pressed that the wax ( 5 ), superficially binds with the polyester resin, but fibers ( 4 ) or straws remain undamaged, and finally attached to the blocks ( 1 ) obtained after curing the boards ( 2 , 3 ) will. 7. The method according to claim 6, characterized by a pressure of 80-700 kp / cm ² . 8. The method according to claim 6 or 7, ge characterized by a press good temperature of around 72 ° Celsius. 9. Apparatus for carrying out the method according to one of claims 6 to 8, characterized marked by a hydraulic press with the pressing material ( 12 ) surrounding heating plates ( 11 ), in which the punch ( 7 ) engages. 10. Process for pressing straw processed into particles into pallets or pallet blocks, or a compact pallet, the straw must be dried to a moisture content of 8-10%, then with unsaturated polyester resin as a binding agent, with the addition of accelerators and hardeners, as a percentage of the unsaturated polyester resin, block on pallet boards or pallets, or a compact pallet is pressed, characterized by the combination of the following process steps

• a) the straw (wheat, corn, rice, etc.) is separated from contamination.
• b) the straw is dried to a moisture content of 8-10%.
• c) Cobalt curing - JOTUN - (cold curing ambient temperature) unsaturated polyester resin, depending on the type weight, from 5-50% of the straw content with approx. 0.001-0.005% hardener nor pol catalyst NO. 13 and 10% cobalt contact accelerator, mix approx. 1-3% of the unsaturated polyester resin. (Setting time approx. 5 minutes).
• d) as an additional filler for straw and unsaturated polyester resin, a fiber connection (glass fiber) can be added as a percentage.
• e) the mix so composed is pressed under a room temperature of 18-30 degrees + Celsius for about 3-5 minutes.
• f) the pressing is carried out at a pressure of 40 kp · cm ² to 700 kp · cm ² .

11. The method according to claim 1, characterized in that the Pallet boards or pallet blocks, or a compact pallet, from a print under which the stamp printing process is pressed.