DE2218051B2 - PROCESS FOR MANUFACTURING POROESE POLYURETHANE FILMS AND THEIR USE - Google Patents

Description

The invention relates to a process for making porous polyurethane films by casting a film of uncured polyurethane on a Ablöseoberf äche and then curing the cast film ⁹ S and subsequent removal of the film and to the use of these porous PoIyurethanfolieii.

According to the prior art, porous foils made of polyurethane are produced in that a solution 3 <> an uncured polyurethane prepolymer A release surface cast the polyurethane composition by removing the solvent and the application of heat is cured and then peeled off from the detachable surface. In order to make the polyurethane films obtained in this way porous, they are mechanically, for example, by piercing the foils are handled by means of needles. on the other hand the porosity is also generated chemically, with granulate materials that are insoluble in the polyurethane * ° but are soluble in other solvents, added to the casting compositions and later removed the foils cast therefrom are removed. The polyurethane compositions are used here, for example Granulate starch added, which is leached with water after the film has been formed, in order to get into the films Leave pores behind.

Such films, which are either self-supporting or for lamination with carrier materials, such as. B. Clothes, paper, plastic od. The like. Are suitable, z. B. in the manufacture of clothing or as Upholstery materials in home, office or automotive equipment used. Polyurethane laminates are also used in shoe manufacture.

The disadvantage of the aforementioned hardening process is that it is relatively expensive and cumbersome to carry out. The polyurethane films produced in this way have the disadvantage that they undesirably adhere or stick to the human hand, which is often inherent in the cured polyurethane film. To eliminate this »deficiency, the foils must be treated, e. For example, by wiping or rubbing with a silicone, or there must adhesion preventing materials, such as silicones or waxes, the Poiyurethanzusammensetzung before casting ° ⁵ are added.

The object of the invention is to create a process for the production of porous polyurethane films, which can be carried out cheaply and easily as well as in the display of a preferred area of use for the polyurethane foils produced by the new process. Furthermore, the adhesive property should be the polyurethane films can be avoided in a simple manner.

The solution to the problem is that in the procedure mentioned in the introduction the unausfphärtetea Polyurethane, in a manner known per se, contains small glass spheres or glass pearls before casting from 1 to 30 parts by weight per 100 parts by weight Polyurethane and with an average diameter of up to about 150μ.

The method according to the invention is cheaper and easier to carry out than the previously mentioned known one Process so that, as a further advantage resulting therefrom, cheaper porous polyurethane films can be produced are. It was surprisingly found that the inclusion of glass spheres or glass beads in the polyurethane film makes these films porous and also deprives them of their adhesive property, so that the Foils no longer stick or stick to the hand. Regarding the elimination of the adhesive property Post-treatment of the cured porous polyurethane films is no longer necessary.

It is believed that the decrease in tackiness is due to the formation of surface irregularities in the films, whereby the film properties are improved and the foils have a matt appearance which prevents sticking. The origin of porosity in the foils can partly be attributed to the greasing of glass beads in the surrounding polyurethane matrix be, in which the remaining glass beads are embedded, which can be achieved by flexible bending or Stretching of the film is caused. More likely the porosity is due to the inability of the hardened Due to the polyurethane composition, the glass beads are firmly glued in it, so that a cavity, surrounding or partially surrounding the pearl is present in the cured composition. if If the glass beads abut close together, the cavities belonging to each bead can be evident Connect together to form a pore or capillary that extends through the thickness of the film extends therethrough.

During the mechanism by which the porosity occurs with the inclusion of glass beads in the foils is not accurately determined, it is believed that relatively few pores due to the removal be formed by glass beads. For example, the films enriched with glass beads have a higher one Wear resistance on than polyurethane compositions without glass beads, which leads to the conclusion that there are a considerable number of glass pearls, even in flexible, or stretched foils. These improved properties of the polyurethane films enriched with glass beads This further distinguishes them from polyurethane films, which are soluble by puncturing or by leaching Additives have been made porous.

The products produced by the process according to the invention can preferably be used for production be used by laminates, which in turn z. B. processed in the textile industry can.

It should also be mentioned that it is known to manufacture rigid cast products made of polyurethane resins with

to produce stored hollow glass spheres. Since such Products should be able to be nailed, d, n. That a nail or the like driven into the product and only overcoming the usually the nail holding, considerable force can be pulled out again, this state of the art does not provide any Instructions for creating the process and the porous polyurethane films according to the invention. Of the Subject of the application, however, does not make use of the hollow spheres made of glass.

The subject matter of the invention is explained in more detail below for a better understanding with the execution of exemplary embodiments

The glass beads embedded in the foils described in more detail below expediently have a diameter less than the thickness desired for the dried film. So z. B. when casting polyurethane film with a dry density of 0.039 to 0.052 mm the inclusion of glass beads that pass through a mesh screen with an ao mesh number of 325 (i.e. glass beads with less than 44 μ in thickness) particularly good results. For thinner foils, glass beads, which are a Pass a mesh sieve with a number of meshes of 400 (less than 37 μ in diameter), preferred. For thicker foils can use larger glass beads, e.g. B. those that use a 100 mesh screen (less than 149 μ) can be included.

There is a direct relationship between the degree of porosity in the polyurethane films is obtained (which is measured, for example, with the aid of the permeability of the films with respect to water), and the Degree with which the foils are enriched with glass beads. With high degrees of enrichment however, factors such as loss of tensile properties and the like may be considered. At low degrees of enrichment from I to 2.5, the Low porosity of the films with respect to water, they however, increases with increasing degree of enrichment. The inclusion of even such a small amount of pearls however, drastically increases the value of the water vapor permeability of the films compared to the water vapor permeability value of a polyurethane film without glass beads. The porosity also increases with a constant degree of enrichment, i.e. i.e. if the glass bead size decreases but the number of glass beads increases, in general, glass bead quantities are apply which vary from 1 to 30 parts by weight per 100 parts by weight of resin. That Resin is uncured and is in the form of a solution in a volatile solvent; i.e., as one solution suitable for pouring.

Glass beads suitable for storage are commercially available. They are uniformly spherical Pearls, e.g. B. from soda lime glass, whose size by sieving in the manner described above or by other facilities is gradually determined. The binding properties of the beads to polyurethane can be achieved by Treatment of the pearls with binders, such as. B. Organosilanes, have been changed, resulting in a Change in film properties leads.

The polyurethane systems in which the glass beads can be incorporated in the present invention are known and have been used extensively so far in the casting of Polyurethanlfilmen and in the manufacture of laminates formed therefrom ⁶ S. The systems commonly used for casting polyurethane films consist of either two-component systems or one-component systems, the latter including paints and masked polyurethanes. ■.

It is state of the art that the two-component systems usually comprise a polyol component which is a solution of a prepolymer includes that by the reaction of an excess is formed from polyester or polyether with a diisocyanate to a prepolymer with a hydroxyl chain end to create. The second component in the system consists of a polyisocyanate, e.g. B. from a diisocyanate or a triisocyanate, or from a prepolymer with an isocyanate termination.

The one-component systems, which also belong to the state of the art, include polyurethane paints a, where z. B. hydroxyl and isocyanate components form a polymer, which then in one suitable solvent is dissolved. These systems also close the so-called blocked isocyanate systems one in which a prepolymer is produced by the reaction of a polyester or a polyether formed with an excess of isocyanate, and the remaining, otherwise reactive Isocyanate groups are formed by reversible reactions with a material, e.g. B. phenol or methyl ethyl ketone ketoxime, blocked. The composition genes further contain a chain extender.

Both the two-component and the one-component systems are expedient hardened by heating for approx. 2 min at a temperature of 121 C or correspondingly longer or shorter at lower or higher temperatures. As is part of the state of the art, you can the approaches contain an assortment of dyes, pigments, fillers, and stretch vibrators, and in addition Catalysts can be provided for the glass beads according to the invention.

The cast foils can either be fully cured for the purpose of lamination and then subsequently by heat sealing or laminated with adhesives, or they can be by touching a substrate with the uncured polyurethane and subsequent curing in place or in laminated to this layer structure.

The following exemplary embodiments make the invention even more understandable.

Example! 1

A polyurethane paint is prepared by reacting an ethylene propylene glycol adipate or a polycaprolactone polyester with a tolylene diisocyanate of 1.75 to 2.0 equivalents per equivalent of ester in the presence of 0.001 to 0.003 weight percent dibutyltin dilaurate as a catalyst. The mixture is heated at 60 to 8O ⁰ C for 1 to 2 hours until the isocyanate content of the reaction mixture reached the theoretical value. At this point a solvent, e.g. B. toluene or xylene, added to stretch the solution to about 67% solids in order to facilitate the stirring of this prepolymer during a subsequent chain extension.

Next, the prepolymer solution is given a solution of an aliphatic amine as a chain extender in a solvent, e.g. B. isopropyl alcohol, ethylene glycol monomethyl ether or isobutyl « alcohol, added. Close the appropriate amines

Materials such as ethylene diamine, hexamethylene diamine or piperazine,

If the resulting solution is viscous, a Selection of thinners are used, e.g. B. with a mixing ratio of 1: 1 from methyl ethyl acetate with isopropyl alcohol

In this solution obtained, which is about 30% solids contains, 5% (percent by weight of the solution) glass beads or glass spheres were stirred in, which passed a mesh sieve with a mesh number of 325 ^. The resulting mixture was then mixed with a doctor blade on a commercial release paper in the form of a coating approximately in thickness 0.100 mm applied. The film obtained was then applied at 12 ° C. by passing it through a heat tunnel cured for 2 min.

After removing the release paper, the porosity of the film was visible by placing the film against strong Light was kept. The film is porous with respect to water, smoke and the like.

The film obtained may suitably be laminated to a substrate such as e.g. B. Cotton fabrics or a non-woven fabric in which acrylic or urethane emulsion adhesives have been used.

Example 2

Glass beads were embedded in a two-component polyurethane system. The system includes one first component, which consists of a hard, rubber-like prepolymer produced by the reaction of a Excess is formed from a polyester with a tolylene diisocyanate. The prepolymer is in Solvents such as B. methyl ethyl ketone or Ethyl acetate dissolved to give a solution containing approximately 25-30% solids.

Just before pouring, add 5% of a second component, which is a solution of a triisocyanate reaction product from trimethylolpropane and tolylene diisocyanate, to the prepolymer with Hydroxyl ends added. The solution of the triisocyanate contains approximately 75% solids in one Solvents such as B. Ethylacevate or ethylene glycol monoacetate. Catalytic or accelerating Amounts of an organometallic catalyst for crosslinking (e.g. a titanium ester) are suitable added. The material obtained has a pot life of approximately 6 hours.

During this period, 5 percent by weight glass beads (based on a 30% resin solution) were in the mixture stored, which was then applied to a base with a doctor blade. The glass beads passed through a 325 mesh screen and the thickness of the film after casting was approximately 0.160 mm. The cast film was then passed through a heat tunnel at 121 ° C for 2 minutes hardened. The surface remained slightly tacky to the touch. The film was rolled up and stored overnight to complete curing, after which no stickiness can be observed was.

Example 3

A number of polyurethane films of various dry thicknesses were made from 10 g samples Urethane resin made. The polyurethane resin, which has an initial viscosity of 12,000 cps, was in each case poured onto a glass plate, treated with a mold release agent, deep-drawn into a film and cured with air drying for 24 h in the presence of moisture.

The water vapor permeability of the films was determined by measuring the water loss from dishes or The bowls determined by the slides against an aqueous calcium nitrate solution in a closed System were tightly covered. The results are shown in Table I below.

* ° Table I.

Film thickness
(mm)

WD-Duich-

nonchalance
(gm / m «24hr)

0.023 183.5 0.031 95.4 0.070 70.5 0.070 66.6 1.120 65.2 0.161 67.2

A second series of films was prepared in the same manner from the same polyurethane, ^a5 been accepted that glass beads of different sizes were mixed in various amounts prior to film formation.

In particular, glass beads with diameters between 0.5 and 20 μ (A) in an amount of 5 and 15 parts by weight per 100 parts by weight of polyurethane were added.

A second glass bead portion (B) with diameters between 6 and 50 μ was in an amount of 5, 15 and 25 parts by weight to 100 parts by weight Polyurethane added.

A third portion (C) with pearl diameters of 53 to 105 μ was used in an amount of 15 parts by weight added.

The water vapor permeability of the films was determined as described above. The results are shown in Table II below.

Table II

Bead size Addition amount Foil thickness
(μ) (parts by weight) (mm)

Water vapor permeability
(gm / ra ¹ 24 hr)

0.5 to 20 1 0.039 103.3 15th 0.047 146.0 6 to 50 5 0.052 88.3 15th 0.060 107.1 25th 0.057 112.5 53 to 105 15th 0.109 ¹ ) 87.9

·) The measured thickness is probably the thickness of the largest existing glass beads (105 μ).

The water vapor permeability of the foils enriched with the glass beads is compared to not beaded polyurethane films of equivalent thickness are shown in Table III below.

Table III

Water vapor permeability in% for foils provided with glass beads compared to foils equivalent Thickness without pearls:

Added amount
(Weight parts /
100 parts by weight polyurethane)

Bead size (μ)

0.5 to 20

6 to SO

53 to 105

18.6%
82.5%

9.1%
45.3%
51.3%

13.0%

From Table III it can be seen that the water vapor permeability increases with increasing enrichment increases and that it increases - with constant enrichment - when the pearl size decreases and the number of pearls increases.

Surprisingly, it resulted in the inclusion of irregularly shaped glass particles in the polyurethane this example shows a decrease in water vapor permeability.

Table IV below gives the percentage change in the water vapor transmission rate for the equivalent Thickness of foils provided with 15 parts by weight to 100 parts by weight of polyurethane, in comparison to polyurethane foils without glass beads, according to:

A) using silica with a particle size of 30 μ,

B) the material according to (A), which was sieved according to a mesh number between 325 and 400,

C) using glass beads with 6 to 50 μ In diameter,

D) the material according to (C), which was sorted according to the mesh number 325, for coarse particles to remove.

Table IV

Percentage change in the water vapor permeability of films with the above additive in comparison to films of equivalent thickness without these additives.

Filler (15 weight parts /
ICO parts by weight
Polyurethane)

A)
B)
C)
D)

19.8%
15.6%
11.6%
10.2%

• 0SS3V43S

Claims (2)

Patent claims: L Process for the production of porous polyurethane films by casting a film of an uncured polyurethane onto a release surface and subsequent curing of the cast film and subsequent peeling off of the film, characterized in that the jin-cured polyurethane is known per se Way before pouring a content of glass beads or glass beads from 1 to 30 parts by weight per 100 parts by weight of polyurethane and with Mix with an average diameter of up to approx. 150 μ. 2. Use of the process products according to claim 1 for the production of laminates.