DE2218051A1 - Porous polyurethane films and several methods of making them - Google Patents

Description

DR. HUGO WiLCKEN ■ DIPL.-ING. THOMAS WICKEN

D - 24 LÜBECK. WIDE STREET 52-54

April 12, 1972 Cz «, / Bö.

Applicant: Potters Industries Inc _o , Carlstadt, 600 Industrial Road,
New Jersey, V _e St.A

Porous polyurethane films and several methods of making them

The invention relates to porous polyurethane films and to several methods for making such films.

The state of the art is with the manufacture of polyurethane films familiar, which is either self-supporting or for amination with carrier materials such as clothing, paper, Plastic or the like are suitable. The laminates obtained can be used, for example, in the manufacture of clothing are or are useful as upholstery materials in home or office equipment or in automobiles «, polyurethane laminates are also used in shoe production.

According to the prior art, polyurethane films are usually formed by a solution of an uncured polyurethane prepolymer is poured onto a dissolving surface and that the polyurethane composition is then cured by removing the solvent and applying heat.

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The polyurethane film obtained can then be applied to a substrate in the manner of a laminate, with heat sealing or Glue to be applied. Alternatively, a cast film of a prepolymer can be a gel process or a gel effect are subjected, but no curing is applied, and such a film is then coated with a substrate material contacted for lamination and cured in place on the substrate.

In many cases it is desirable that such films be made porous. In a known way, this becomes present carried out by mechanical means, for example by piercing the film with needles or also by chemical means Facilities. For this last purpose, granular materials that are insoluble in the polyurethanes but soluble in other solvents are added to the casting compositions and later removed from the films cast therefrom. For example Granular starch has been added to the polyurethane compositions prior to curing. After film formation, the Starch leached with water to leave pores in the film.

According to the invention it was found that the inclusion of glass beads or glass spheres in the films make these films porous. It also reduces or eliminates the presence of the glass beads in the films, the setting of the films and the unacceptable sticking or sticking of the films to the hand that causes the cured Polyurethane films are often peculiar to. Currently muli this

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sticky feel can be overcome by post-treatment of the film (for example by wiping with a silicone) or by adding materials, such as silicones or waxes, to the composition gate the pouring.

It is believed that the tackiness reduction brought about by the addition of glass beads to the films is due to the introduction of surface irregularities in the films, thereby improving the film properties and the films show a matt appearance which prevents setting. The development or manufacture the porosity in the films can be due in part to physical loss of glass beads from the surrounding polyurethane matrix in which they are embedded after the pearls have moved, 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 cured polyurethane composition due to glue the glass beads firmly in it, so that a cavity that surrounds the bead or partially surrounds, is present in the cured composition. If there are small pearls close together, they can the cavities belonging to each bead obviously connect with one another to form a pore or capillary which extends through the thickness of the film.

While the mechanism by which the intercalation of glass beads in the films introduces the porosity "cannot be precisely determined, it is assumed that relatively few

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Pores are formed by the removal of glass beads. For example, the films enriched with glass beads have a higher wear resistance than the same polyurethane compositions to which glass beads have not been added, which leads to the conclusion that there are a considerable number of glass beads, even flexibly bent ones or stretched films. These improved properties of the glass bead-enriched polyurethane resin compositions further distinguish these from polyurethane films, such as by puncturing or by leaching of soluble additives for example starch, have been made porous.

The polyurethane films of greatest commercial interest at present vary in thickness from about one mil to about six mils, with a thickness between 1.5 to 2 mils predominating. These thickness specifications refer to the dried cured film and not to a film that has just been cast onto a release surface. The film that has just been cast contains solvent and can be three times as thick as the cured film from which the solvent was removed _e

The glass beads embedded in the film expediently have a diameter that is smaller than the thickness for the dried film is desired. For example, when casting polyurethane films with a dry thickness from 1.5 to 2 mils of inclusion of glass beads passing through a 325 mesh screen (i.e. Güaeper-

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len less than 44 microns in thickness) are particularly good Results. For thinner films, glass beads and a mesh screen are used 400 mesh (less than 37 microns in diameter), pre-sucked. For thicker films you can larger glass beads, such as those that will pass through a 100 mesh screen (less than 149 microns) suitably included.

There is a direct relationship between the degree of porosity obtained in the polyurethane films (which is measured, for example, by means of the permeability of the films with respect to water liquid) and the degree to which the films become enriched with glass beads. At high degrees of enrichment, however, other factors such as loss of strength properties and the like must be taken into account. In general, amounts of glass beads varying from 1 to 30 parts per 100 parts of resin (phr) have been used unhardened and in the form of a solution in a volatile solvent, that is, as a solution suitable for casting.) With a glass enrichment of 1 to 2.5 phr, the porosity of the films in suction on water liquid is low, but it increases with dea degree of security to. The inclusion of even such a small Pesflent & eage, however, drastically increases the value of the water vapor permeability through the films compared to d & m ¥ ®sserdifi £ apfdwi? C; hlis worth, through a polyurethane filler In άΦΜ sic-ii It.qI & g ¹ SiS ₁ S are located . Also increases sioL ac ^. © iiieii InQai? Taat ©? I. M & i-

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The degree of porosity as the glass bead size decreases, that is, as the number of beads increases.

Glass beads suitable for storage are commercially available. They are uniformly spherical pearls, for example made of soda-lime glass, the size of which by sieving in that described above Type or is gradually determined by other institutions. The binding properties of the beads to polyurethane can be changed by treating the beads with binders such as organosilanes prior to admixing with an uncured polyurethane, which leads to a change in the film properties.

The polyurethane systems in which the glass beads can be incorporated in accordance with the present invention are well known in the art and so far in the casting of polyurethane films and in the manufacture has been extensively used by laminates formed therefrom. The most common systems for casting polyurethane films consist either of two-component systems or of one-component systems, the latter being lacquers and hardened Include (blocked) polyurethanes.

It is state of the art that the two-component systems usually a polyol component comprising die.eine solution of a prepolymer enclosing which by the reaction of a Excess of polyester or polyether with a diisocyanate is formed to form a prepolymer with a hydroxide termination to create. The second component in the system consists of

209844/1172

a Polyisozyanat, for example from a Biisosyanat or a triisocyanate, or from a prepolymer with an isocyanate termination. The two-component systems are before the Pour admixed on a release surface, and hardening is effected by their interaction, suitably in the presence of a catalyst (see US Pat. No. 3,539,424).

The one-component systems also belonging to the prior art include polyurethane lacquers in which, for example, hydroxide and isocyanate components have undergone a preliminary reaction to form a polymer which is then dissolved in a suitable solvent. These systems also include the so-called mocked isocyanate systems, in which a prepolymer is formed by the reaction of a polyester or a polyether with an excess of isocyanate, and the remaining, otherwise reactive isocyanate groups are formed by reversible reactions a material, for example phenol or methyl ethyl ketone ketoxime, blocked. The compositions further contain a chain extender.

When the set system is poured onto a release surface and is heated to cure, the free chemical combination of the setting agent dissociates with the isocyanate groups, and the isocyanate groups released again react with the chain extender to cause hardening. Both the Two-component and one-component systems are expedient built to by warming for about two

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Minutes at a temperature of 121 ° C, or correspondingly longer or shorter at lower temperatures or higher temperatures. As is part of the state of the art, the frames can contain a selection of dyes, pigments, Contain fillers and extenders, and in addition to the glass beads of the invention, catalysts may be provided be.

As noted above, the cast films can either be fully cured and then laminated for lamination by heat sealing or laminated with adhesives, or they can be laminated by touching a substrate with the uncured Polyurethane and subsequent curing of the composition in place or laminated in this layer structure will.

A better understanding of the present invention and many of its advantages can be obtained by referring to the following special embodiments, which are explained in more detail below.

example 1

A polyurethane varnish is prepared by reacting an ethylene propylene adipate or a polycaprolactone polyester with a toluene diisocyanate of 1.75 to 2.0 equivalents per equivalent of ester in the presence of 0.001 to 0.003 weight percent a dibutyltin dilaurate as a catalyst. The mixture

BATH ORIGINAL

2098U / 117?

is heated to 60 to 80 ° C for one to two hours until the isocyanate content of the reaction mixture reaches the theoretical value. At this point, a solvent of, for example, toluene or xylene is added to dilute the solution to approximately 67% solids in order to facilitate stirring of this prepolymer during a subsequent chain expansion step.

Next, a solution of a chain-building aliphatic amine in a solvent such as isopropyl alcohol, methyl cellulose solvent (methyl cellosolve) or isobutyl alcohol is added to the prepolymer solution. The suitable amines include materials such as ethylene diamine, hexamethylene diamine and piperazine. The final solvent composition is suitably 80 to 85 hydroxydisch i> and 20 to 15 # aromatic with a solids content of about 25 ^.

If the resulting solution is too viscous, a choice of Thinners are used, for example with a mixing ratio of 1: 1 of methyl ethyl ketone with isopropyl alcohol.

In this solution obtained that is about $ 30 solids contains, 5 # (percent by weight of the solution) glass beads or glass spheres were stirred into a mesh sieve with a number of meshes of 325 happened. The resulting mixture was then applied to a commercial release paper in the form of a doctor blade Coating applied to a thickness of approximately 6 mils. Of the

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The resulting film was then cured at 121 ° C. by passing it through a heat tunnel for two minutes.

After removal from the release paper, the porosity of the film was visible by holding the film against strong light. The film is porous with respect to a water liquid, smoke and like that.

The obtained film may be suitably laminated with a substrate such as cotton cloth or a nonwoven bonded fiber substrate using acrylic or urethane emulsion adhesive be used.

Example 2

Glass beads were embedded in a two-component polyurethane system, which is commercially available under the trademark "Imp ranil" is available. The system includes a first component, which consists of a hard rubber-like prepolymer which is through the reaction of an excess of a polyester with a toluene diisocyanate is formed. The prepolymer is in solvents such as methyl ethyl ketone or ethyl acetate dissolved to give a solution that is about 25 to 30 # Contains solid parts.

Just before casting, 5 % of a second component, which comprises a solution of a triisocyanate reaction product of trimethylolpropane and TouoldiisoByanat, is added to the prepolymer with hydroxide termination. The solution of the isocyanate material

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contains approximately 75 ί> solids in a solvent such as ethyl acetate or cellosolve acetate. Catalytic amounts of an organometallic catalyst for the crosslinking reaction (e.g. a titanate ester accelerator) are suitably 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 incorporated into the mixture, which was then applied to a double sided release sheet with a doctor blade. The glass beads passed through a 325 mesh screen and the thickness of the film after casting was approximately 6 mils. The cast film was then cured by passing it through a heat tunnel at 121 ° C for 2 minutes. The surface remained in relation Slightly sticky to the touch. The film was rolled up and stored overnight to complete curing, followed by no stickiness was noticeable on the product.

Example 3

A number of polyurethane films of various dry thicknesses were obtained from 10 gram samples of number 347 urethane resin commercially available from Chemical Components Inc., Hanover, New Jersey. The resin, which has an initial viscosity of 12,000 centipoises, was in each case poured onto a glass plate, treated with a mold release composition, thermoformed into a film

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- 12 and, if air-dried, moisture-cured for 24 hours.

The water vapor transmission rate of the films was determined by measuring the water loss from bowls or bowls that were passed through the films were tightly covered against an aqueous calcium nitrate solution in a closed system. The results are reproduced in Table I below.

Table I: Dry film density WD permeability (mils) (gm / rn ² 24 hr) 0.9 183.5 1.2 95.4 2.7 70.5 2.7 66.6 4.6 65.2 6.2 67.2

A second series of films was made from the same in the same way Resin prepared except that glass beads of various sizes add resin in various amounts prior to film formation was added.

In particular, glass beads with diameters between 0.5 to 20 microns (A) in the order of magnitude or in degrees of enrichment of 5 and 15 phr were added.

A second portion of glass beads (B) with diameters between 6 and 50 microns was used with enrichment levels of 5, 15 and 25 phr

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added.

A third portion (C) with bead diameters from 53 to microns was added to the resin at an enrichment level of 15 phr added.

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

Table II: Added amount
(phr) Dry film thickness
(mils) Steam
permeability
(gm / m2 24 hr) Pearl size
(Micron) 5
15th 1.5
1.8 103.3
146.0 0.5 - 20 5
15th
25th 2.0
2.3
2.2 88.3
107.1
112.5 6-50 15th 4.2 * 87.9 53-105

* The measured thickness is likely the thickness of the largest glass beads available (105 microns = 4.1 miIj of this math The connection also applies to the other mil information).

* Microscopic examination of a cross section showed the film between glass beads that were approximately 2 mils thick.

The water vapor permeability of the enriched with the glass beads Films is of equivalent thickness compared to non-beaded polyurethane films in the following Table III reproduced.

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Table III:

Water vapor permeability in # for with (glass beads Films compared to films of equivalent thickness without the addition of pearls:

(Ear) Pearl size (Micron): 53-105 Added amount 0.5 - 20 6-50 13.0 5
15th
25th 18.6
82.5 9.1
45.3
51.3

It is evident from Table III that it is the water vapor permeability increases with increasing enrichment and that it increases - with constant enrichment - if the Pearl size decreases and the number of pearls increases.

Surprisingly, the inclusion resulted in irregularly shaped ones vitreous particles in the polyurethane resin of this example in a decrease in the water vapor permeability of the enriched Film versus a non-enriched resin film.

Table IV below gives the percentage change in water vapor permeability for equivalent thickness of films, which were enriched with 15 phr, in comparison to non-enriched polyurethane films, according to:

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(A) using silica flour in the order of magnitude of 30 microns (100 # less than 44 microns in size) which is available under the trademark "Min-U-Sil" is commercially available,

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

(C) using glass beads 6 to 50 microns in diameter,

(D) The material according to (C), which has been sorted according to the mesh number 325 to give coarse particles remove.

Table IV:

Percentage change in water vapor permeability of enriched Films versus non-enriched films of equivalent thickness:

Filler (15 phr)

A) 19.8 B) 15.6 C) + 11c6 D) + 10.2

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Claims (6)

PATENT LAWYERS? 2 Ί 8 O 5 1 DR. HUGO WILCKEN DIPL.-ING. THOMAS WILCKEN D - 24 LÜBECK. BREITE STRASSE 52-54 AU April 11, 1972 Ce.Bö. Applicant: Potters Industries Inc., Carlstadt 600 Industrial Road, New Jersey, V.St.A. Claims 1. Process for the production of a polyurethane film by Casting a film of an uncured polyurethane resin on a release surface and then curing it of the cast film, characterized in that the uncured resin before casting glass spheres or glass beads are mixed, whereby the cured cast film is made porous. 2. The method according to claim 1, characterized in that the Glass beads in the uncured resin in an amount up to 30 parts by weight per 100 parts by weight of said Resin can be stored. 3. The method according to claim 1 or 2, characterized in that the glass beads have an average diameter of up to about 150 microns. 209844 / 1-172 4. The method according to claims 1 »2 or 3, thereby marked« shows that the cured cast film has a thickness between about 1 mil and 6 mils. 5. The method according to one or more of claims 1 to 4 »characterized» that the porous polyurethane film according to is laminated with a carrier layer after curing. 6. The method according to claims 1 to 4 # characterized in that that the cast film is laminated after partial curing with a carrier and then further on this carrier is cured, whereby a porous cured polyurethane film is formed on the carrier * 7 »Porous polyurethane filii, characterized in that it has a Matrix made of a hardened polyurethane resin with glass beads or glass spheres distributed therein 8ο film according to claim 7, characterized in that it is the Contains glass beads in an amount up to 30 parts by weight per 100 parts by weight of said resin. 9 »Film according to claim 7 or 8, characterized in that the glass beads have an average diameter of up to approximately 150 microns. according to claim 7, 8 or 9, characterized in that it has a thickness between about 1 mil and 6 mil. - 2-20 98 4 kl 117 2 TL film according to one or more of the claims? to 10, characterized in that it is laminated onto a carrier is. 20M44 / 1172