DE1729025B1 - PROCESS FOR PRODUCING A NET-LIKE MATERIAL FROM A THERMOPLASTIC PLASTIC WITH A FIBER STRUCTURE - Google Patents

Description

1 2

The invention relates to a method for producing the reticulated material according to the invention of a new reticulated material from a thermo- not yet proven to be known plastic plastic with fiber structure. Synthetic plastics that are applied A process is already known in which crystalline polyolefins, such as polyethylene, are higher next a film tube with a closed 5 density (melt index according to ASTM1238-52T, Cell structure made by melt extrusion 0.04 ~ 8), a low density polyethylene (melt will and then at least 50% of the ge index 0.3 ~ 7), polypropylene (melt index 0.3 ~ 14), closed cells by inflating the foil - an ethylene - propylene - copolymer (melt tube with air or a pumped-in liquid- index 0.3 ~ 14), polyester (molecular weight 8000 ability or by the application of heat, with an io ~ 13000), polyamides (molecular weight 11000 considerable shrinkage energy is applied, since ~ 30000) and other thermoplastic resins that with the closed cells are destroyed, form a stretchable film, are torn and a web is obtained, whose It is possible to continue dyes, stabilizers Structure is similar to that of a fiber fleece. By mixing this into the raw plastic. Inflation, however, easily escapes the air or the 15 commercially available plastics with a stabilizer, pumped-in liquid through the cracked cells- a lubricant and an antistatic agent len, enlarges the holes and reduces the internal can as a starting material without special Schwie-stretching pressure. It is therefore difficult to use the skills.

Most of the closed cells are completely expanded - Commercially available foaming agents are

tear down. Due to the heat shrinking, it also seems to be used comfortably. For example, an azo

difficult to find most parts of the closed compound, such as azodicarbonamide, a sulfonyl

Rupture cells when the procedure is used with other semicarbazide, such as ρ, ρ'-oxybisbenzenesulfonylsemicarb-

Plastics is used as styrene resins. From azide, toluenesulfonylsemicarbazide, a sulfonylhj'-

the drawings of the British patent is too drazid, such as ρ, ρ'-oxybisbenzenesulfonylhydrazide or

infer that the product is not a cobweb-like 25 a nitroso compound such as dinitrosopentamethylene

Stcff is, but rather corresponds to a fiber fleece. tetramin, as well as a solvent and other additives

The invention is based on the object to be used.

drive of the type mentioned at the beginning, the proportion of foaming agent in the thermo-

to which the cells of the material to be processed is a possible plastic resin-foaming agent mixture

lends completely and with less effort to 30 0.1 to 2 percent by weight, preferably 0.2 to 1 weight

can be ured. weight percentage. When the foaming agent is in

In order to achieve this object, according to the invention, an amount smaller than this range is used

suggested that a molten mixture is made, the distribution of the perforated cells of the

poor in a stretchable thermoplastic resin and porous film or sheet according to the invention,

0.1 to 2 percent by weight of the molten Ge 35 while with a higher amount of foaming

Mixing a foaming agent with an agent increases the strength of the porous film or sheet

Slot is reduced at temperatures of a maximum of 30 ⁰ C above, so that the stretching to increased

the decomposition temperature of the foaming agent leads to scrap.

to a porous film or sheet from 0.03 to 0.5 mm Depending on the desired grip of the net-

Thick with numerous perforated cells extruded 40-like material can filler in an amount of

and the lengthwise porous film or sheet to about 1 to 10 percent by weight based on the resin,

200 to 800% of the length is stretched. be used.

In Fig. Fig. 1 is a schematic of the structure of an exemplary embodiment of the porous eyelets Film or arc explained after leaving the making. First, a mixture of therdem Slot indicated; 45 thermoplastic resin and foaming agent

F i g. 2 shows a net-like material, which through the melt in the form of a porous film or body

Stretching the porous film or sheet to form essentially closed cells

F i g. 1 has been manufactured. is free, extruded. As an extruder can be an ordinary

The net-like material according to the invention can be used as a flat film extruder with a T-head piece or a Knitting yarn or as a filling material for pillows are used 50 ring film extruder with one ring-shaped, one. The net-like material according to the invention has a cooled head piece having an inner mandrel of great durability and has a nice turn. It will have a cell diameter of Appearance, since the good properties of the material preferred as a maximum of 3 mm.

The porous film or sheet must be from the head piece

plastic plastic can be retained in the product with a certain ratio to the extrusion

the. sion speed standing take-off speed

The handle of the net-like material obtained can be removed from, whereby the type and amount of

The thermoplastic material can, depending on the foaming agent and the working temperature, a

The stretching method used will play a role. The specific critical processing

the. 60 speed ratio is defined as follows:

Specific critical processing _ extrusion speed of the mass (g / minute mm ² ) speed ratio ~ take-off speed (m / minute)

For example, the specific critical screw of 40 rpm ... 0.17 with a screw-tight processing speed ratios 0.15 at a speed of 50 rpm. If the porous film is too thick for one revolution of the extruder or sheet, the cells remain closed

in the film, and by stretching this porous film or sheet, a reticulated material cannot be obtained. On the other hand, if the porous film or sheet is too thin, the perforated cells are randomly distributed. In order to decompose the foaming agent, the extrusion temperature must be higher than the decomposition temperature of the foaming agent. The preferred temperatures for the melt extrusion can be used by the type of plastic and a foaming agent, is determined, but are usually a maximum of 3O ⁰ C higher than the decomposition temperature of the verwend; th foaming. On the other hand, the stretching temperature depends on the plastic used, preferably the stretching temperature z. B. 120 to 150 ⁰ C for polypropylene, 100 to 140 ° C for high density polyethylene and an ethylene-propylene copolymer and 80 to 120 ° C for a low density polyethylene.

When the porous film or sheet is stretched into strips for use as a knitting yarn is cut, cutting devices, e.g. B. Knife at the distance of the desired strip width, arranged so that the film or sheet is cut into strips at the withdrawal speed of the sheet will. It is also possible to cut the porous film or sheet into strips after the sheet has been stretched. If the porous film or sheet is cut after stretching, it can be stretched more, giving the reticulated stripes a good fiber structure, a higher degree the network formation and a lower roughening at the interfaces.

If a reticulated strip with a soft hand is desired, the preferred degree of stretching is 300 to 500% of the original length.

example 1

Azodicarbonamide is dry mixed as a foaming agent into a commercially available polypropylene (melt index 8) suitable for the production of films by the usual method using a ribbon blender, so that the mixture contains 0.5 percent by weight of azodicarbonamide. The mixture of raw materials is extruded by means of an inclined downwardly inclined ring film extruder, which has a Külerdorn (screw diameter 40 mm, L / D 22, head piece diameter 75 mm, mandrel diameter 95.5 mm) with a screw speed of 60 rpm, a temperature at Head piece of 205 ⁰ C and a withdrawal speed of 12 m / minute. The extruded tube of film is a porous film or sheet with numerous perforated cells and contains essentially no closed cells. The porous film or sheet thus produced is pre-heated by being passed through three heated to 100 ⁰ C carrying roller pairs, and is longitudinally stretched by passage through two Verstreckwalzenpaare and then stretched further in the longitudinal direction and cooled by three drawing and cooling roller pairs. The speed ratio of the preheated conveyor rollers to that of the two stretching and cooling rollers is set to 1: 5. Are heated for two stretching rollers 130 and 14O ⁰ C and disposed between the conveying and preheating and final stretching and cooling rolls. The porous film or sheet is thereby stretched to 400% of its original length.

In this way, a net-like material with a fiber structure and small crimps along the direction of the material with a very soft feel is obtained. The net-like material has a strength of 1.62 g / D, an elongation of 14% and a Young's modulus of 100 kg / mm ² .

Examples 2 to 5

The same foaming agent as in Example 1 is kneaded into polyethylene having a density of 0.923 and a melt index of 4, using the usual method by means of a mixer, so that a base of 10% by weight of the foaming agent is obtained. This basic approach is mixed into a polypropylene copolymer which contains 2.5% polymerized polyethylene as a block (viscosity number of the copolymer 1.65), two mixtures being obtained which contain 0.2 and 0.5 percent by weight of the foaming agent, based on the resin. The two mixtures obtained are extruded by means of a film extruder with a T-head piece (screw diameter 50 mm, L / D 20, compression ratio 4.0, head piece width 280 mm) with a screw speed of 40 rpm and a head piece temperature of 215 ^° C.

If the porous film or sheet with no closed cells is picked up, the sheet becomes moving cut into strips with a width of 50 mm by means of knives, which are arranged at a distance of 50 mm. The strips produced in this way are in the longitudinal direction in the same way as in Example 1 on two different Stretching degrees stretched, namely 400 and 500% of the original length. The mechanical Properties and feel of the resulting reticulate material with fiber structure are in the listed in the following table.

lot
Ver
look
mingling
middle
(Vo) Ver
stretch
k-
Degree
( ¹ yo) Firm
speed
(g / D) Deh
potential
Degree
( ⁰ U) Young
module
(kg /
mm ² ) handle 2
50 3
4th
5 0.2
0.2
0.5
0.5 400
500
400
500 2.40
2.71
1.61
1.70 18th
16
15th
14th 230
270
72
94 1 something
[hard
J and stiff
!Very
J soft

Example 6

The same foaming agent is blended into the same polypropylene as in Example 1 and more 0.02 parts by weight of a cyanine blue pigment are mixed in in the same way as in the basic batch.

A net-like material with a fiber structure is produced in the same way as in Example 1 from the basic batch obtained. The net-like material had a strength of 1.69 g / D, a degree of stretching of 15% and a Young's modulus of 97 kg / mm ² . Compared to the net-like material obtained according to Examples 1 to 5, the stretched

th stripes a greater transparency and a pearl-like sheen.

Example 7

The basic batches of Examples 2 to 5 containing the foaming agent are carried out with commercially available High density polyethylene (melt index 6.5) dry mixed, so that the foaming agent Azodicarbonamide is present in polyethylene in an amount of 0.7 percent by weight.

The mixture obtained is passed through the extruder used in Example 1 under the same conditions extruded to produce a tubular porous film or sheet without closed cells.

The porous film or sheet obtained is passed through three pairs of conveying and preheating rollers, which are heated to 100 ° C., stretched in the longitudinal direction while passing through two pairs of stretching rollers and further stretched and cooled by means of two final pairs of stretching and cooling rollers. The speed ratio of the conveying and preheating rollers to that of the two final pairs of drawing and cooling rollers is set to 1: 3.5. Between the conveying and preheating rolls and the stretching and cooling rolls two Verstreckwakenpaare are arranged, which are heated to 125 ⁰ C. The porous film or sheet is thereby stretched to 350% of its original length. The net-like material with a fiber structure produced in this way does not show any curls as in the case of polypropylene, but has a very soft feel. After the final stretching, the net-like material is cut into strips which have a strength of 0.37 g / D, a degree of elongation of 9.36% and a Young's modulus of 33.8 kg / mm ² .

Example 8

In commercially available polyethylene (melt index 1.6, density 0.921), azodicarbonamide is used as a foaming agent and lead stearate as a foaming aid by the usual method using a Ribbon mixer mixed in as in Example 1, so that 0.7 percent by weight of foaming agent and 0.1 percent by weight Foaming auxiliaries, based on the polyethylene, are present in the mixture.

The mixture obtained is extruded by means of an extruder with a T-head piece as in Examples 2 to 5, with screw speeds of 40 rpm and a head piece ^{temperature of 185 °} C., whereby a porous film or sheet without closed cells is produced.

The sheet is cut into strips 50 mm wide and 500% of the original length in the longitudinal direction Length drawn according to the procedure of Example 1 at 95 ° C. The reticulated stripes with a fiber structure have a soft handle and a strength of 1.4 g / D and a degree of elongation of 30%.

Claims (2)

Patent claims: 1. A method for producing a reticulated material from a thermoplastic material with fiber structure, characterized in that a molten mixture of a stretchable thermoplastic resin; and 0.1 to 2 percent by weight of the molten mixture a foaming agent through a slot to temperatures of a maximum of 30 ° C above the Decomposition temperature of the foaming agent into a porous film or sheet from 0.03 to 0.5mm thick with numerous perforated cells and extruded the porous film or sheet in Is stretched longitudinally to 200 to 800% of the length. 2. The method according to claim 1, characterized in that the porous film or sheet before or cut into strips after stretching. 1 sheet of drawings