JPH0253447B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing a non-porous, moisture-permeable polyurethane film suitable for various materials such as moisture-permeable gloves, rainwear, agricultural cover films, and food packaging films. (Prior art) Materials such as moisture-permeable gloves, rainwear, agricultural cover films, and food packaging films allow moisture to pass through from inside and outside due to their uses, but they also allow moisture to pass through from outside, as well as microorganisms such as bacteria and microorganisms. The impermeability of dirt and grime is a commonly important factor, and for this reason, various proposals have been made regarding methods for producing porous or non-porous moisture permeable polyurethane films. (USP4181127,
WO85-5373, JP-A-180152, JP-A-59-
140217, JP-A-59-140219, JP-A-59-159338,
(Japanese Patent Laid-Open No. 60-135245, etc.) During many of these trials, porous films have both moisture permeability and air permeability, making them preferred materials, but they are not suitable for special applications such as medical gloves and food packaging films. However, it was difficult to prevent the infiltration of bacteria and microscopic dirt from the outside, and it was not suitable for use. These drawbacks of porous films can be overcome by using films made of non-porous and moisture permeable polyurethane polymers. As a means of imparting moisture permeability to a non-porous polyurethane film, it is well known to use polyethylene glycol or a block copolymer of ethylene oxide and propylene oxide as a polyol component. For films made using these conventional hydrophilic polyurethane polymers,
Increasing the polyoxyethylene content in the final polymer to ensure the desired moisture permeability resulted in a significant increase in water absorption and swelling, which resulted in a problem in that the physical properties of the polymer film when wet were deteriorated. For example, JP-A-59-
No. 158252 discloses a hydrophilic polyurethane resin containing a large amount of oxyethylene groups, which swells with water but has film-forming ability. vice versa,
If the polyoxyethylene content is lowered, water absorption and swelling resistance will be improved, but moisture permeability will be lowered, which is not preferable. JP-A-60-6775 describes a non-porous film made of an ester polyurethane polymer that does not contain any oxyethylene groups. Although this film is highly flexible and elastic, and has low wettability when wet, it has the drawback of insufficient moisture permeability. Non-porous moisture-permeable films made of polyurethane polymers using polyoxyethylene glycol alone or in combination with polyoxypropylene glycol as a polyol component, or a copolymer of both, are produced in proportion to the polyoxyethylene content. ,
Polymers tend to swell more when they absorb water, and when they swell, they have the disadvantage of causing a significant drop in strength, so they cannot be used as materials for moisture-permeable gloves, rainwear, cover films for food packaging, etc. Furthermore, ester polyurethane polymers developed as non-swellable materials have the drawback of insufficient moisture permeability as non-porous films. (Problems to be Solved by the Invention) An object of the present invention is to provide a method for producing a polyurethane film that is non-porous and has moisture permeability. Another object of the present invention is to provide a method for producing a polyurethane film that has water absorption and swelling resistance and also has excellent strength even when wet. (Means for Solving the Problems) The present invention involves reacting polyethylene glycol with a molecular weight of 200 to 600 with an organic dicarboxylic acid alone or an organic dicarboxylic acid with ε-caprolactone and/or a short chain polyol to reduce the polyoxyethylene content. but
17-70% to form a polyether-ester polyol with a molecular weight of 500-3000, and the polyether-ester polyol is reacted with an organic polyisocyanate in the presence of a chain extender to give a polyoxyethylene content of 15-62%. The present invention relates to a method for producing a non-porous moisture permeable polyurethane film using a polyurethane polymer, characterized in that the weight % range is within the range of % by weight. The polyurethane polymer used in the present invention is a multi-block copolymer in which a polyether chain with a specific molecular weight as a hydrophilic component, a polyester chain as a hydrophobic component, and polyurea and/or polyurethane blocks as hard segments are linearly connected. Although it contains a relatively large amount of oxyethylene groups, it is a polymer that has extremely low water absorption swelling properties. In producing the polyurethane polymer used in the present invention, the molecular weight of the polyethylene glycol used is preferably in the range of 200 to 600. When the molecular weight is within this range, a suitable moisture permeability coefficient and swelling rate can be obtained. The organic dicarboxylic acid is not particularly limited as long as it can undergo an esterification reaction with polyethylene glycol, but particularly preferred examples include adipic acid and isophthalic acid. For example, ε-caprolactone undergoes ring-opening polymerization in the presence of a tetrabutyl titanate catalyst, starting from the terminal hydroxyl group, and contributes to the production of polyether-ester polyol. Examples of short chain polyols include ethylene glycol, 1,3-
Examples include propylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol. The polyether-ester polyol obtained by the reaction of the above polyethylene glycol, organic dicarboxylic acid alone or organic dicarboxylic acid with ε-caprolactone and/or short chain polyol has a polyoxyethylene content of 17 to 70% by weight, The molecular weight is in the range of 500 to 3000. If the polyoxyethylene content exceeds 70% by weight, the film formed from the final polyurethane polymer will have extremely poor water absorption and swelling properties, making it impractical. Moreover, if it is less than 17% by weight, the moisture permeability of the film will be poor. Furthermore, if the molecular weight exceeds 3,000, the strength of the film formed from the final polyurethane polymer will drop significantly and become unusable, while if it is less than 500, the tensile strength
The elongation and flexibility decrease, making it impractical. The organic polyisocyanate used in the present invention may be any polyisocyanate known in polyurethane chemistry, for example hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate, 2,4 -Tolylene diisocyanate (2,4-TDI), 2,
6-tolylene diisocyanate (2,6-TDI),
4,4'-diphenylmethane diisocyanate (MDI), carbodiimide modified MDI, polymethylene polyphenyl polyisocyanate (PAPI),
Ortho-toluidine diisocyanate (TODI),
Examples include naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), etc.
A species or two or more species can be used. All known chain extenders can be used, such as diols such as ethylene glycol, 1,4-butanediol, and neopentyl glycol, 4,4-methylenebis(2-chloroaniline), isophoronediamine, Pepyrazine,
Examples include diamines such as ethylenediamine, amino alcohols such as N-methylethanolamine, and monoethanolamine. The polyurethane polymer of the present invention obtained by reacting the above-specified polyether-ester polyol with an organic polyisocyanate in the presence of a chain extender has a polyoxyethylene content in the range of 15 to 62% by weight. If the polyoxyethylene content is less than 15% by weight, the moisture permeability will be poor.
Moreover, if it exceeds 62% by weight, the swelling ratio will increase, causing problems in practical use. The above polyether-ester polyol can be produced without a solvent;
In producing a polyurethane polymer from an ester polyol, an organic solvent such as dimethylformamide (DMF) can be suitably used. Although either a prepolymer method or a one-shot method can be employed for this urethanization reaction, the prepolymer method is more suitable from the viewpoint of structural regularity of the produced polymer. The solids content in the polyurethane polymer solution thus produced is preferably in the range of about 10 to 70% by weight, particularly preferably in the range of about 30 to 50% by weight. The present invention uses a continuous coating device to apply a solvent solution of a polyurethane polymer onto a release paper, then passes it through a drying oven to dry the solvent, and then peels the formed film from the release paper. A continuous method for producing a polyurethane film comprising the steps of peeling or peeling and winding up on a take-up roll, the method comprising using the above polyurethane polymer as the polyurethane polymer. Related. In the present invention, the solvent solution of the polyurethane polymer is preferably diluted with a diluent such as DMF, methyl ethyl ketone (MEK), toluene, or a chlorinated solvent, and exhibits a viscosity of about 2000 to 3000 cps during coating. It is also possible to add silicone surfactants, weathering agents, pigments, and other additives as appropriate. As the release paper on which the solvent solution of the polyurethane polymer for coating is applied, polyethylene terephthalate (PET) film, polyethylene laminate paper, etc. are suitable. As a continuous coating device, various devices such as a roll coater, knife coater, bar coater, reverse coater, comma coater, etc. can be used. As an example, FIG. 1 schematically shows a coating process using a comma coater. In the figure, 1. release paper feeder; 2. Back crawl, 3. Comma coater, 4. Suction type feed belt, 5. Drying oven, 6. cooling drum, 7. Suction type tension rule, 8. Film winder, 9. Solvent solution of polyurethane polymer, 10. Liquid feed pump, 1
1. This is a release paper winder. Depending on the application, the film can be wound up on the film winder 8 together with the release paper without using the release paper winder 11. In this case, it is also possible to process the film into a film of desired dimensions using other known rewinder/slitter machines. Drying of the coating film is approximately 0.5 to 70 to 120℃.
It is preferable to carry out the process for about 2 minutes, and the thickness of the formed film is preferably in the range of about 10 to 50 μm. The non-porous moisture-permeable polyurethane film obtained by the present invention has good tensile strength, so there is no fear of tearing when peeling the film formed by a continuous coating device from a release paper, making it efficient and stable. Production is possible. In addition, since the water absorption swelling rate is 15% or less (in the examples shown in Table 2, it is often zero), the decline in physical properties due to swelling during wetness can be suppressed, and depending on the application, it can be made as thin as 10μ. is also possible. In particular, when a formulation with a water absorption swelling rate of 0 is selected, even when water droplets adhere to the surface of the product film, no local blistering phenomenon is observed, making it suitable for use in gloves, rainwear, film covers, packaging materials, etc. This property is extremely suitable for practical use as a material. (Example) Next, the present invention will be specifically described based on Examples. In addition, parts or % simply refer to parts by weight or weight %.
shows. Reference Examples 1 to 7 and Comparative Examples 1 to 4 Polyethylene glycol, organic dicarboxylic acid, and ε-caprolactone were mixed in the proportions shown in Table 1, 0.001% of tetrabutyl titanate was added as a catalyst, and the mixture was mixed in a flask. under stirring, 200
Ring-opening polymerization and esterification of ε-caprolactone were performed by heating at ~210°C. The reaction was continued for 20 hours and dehydration was performed under reduced pressure to obtain polyether-ester polyols A to J. The polyoxyethylene content and molecular weight calculated from these mixing ratios were as shown in Table 1. In Table 1, PEG represents polyethylene glycol, PEEP represents polyether-ester polyol, and EO represents polyoxyethylene. Next, using the polyether-ester polyol shown in Table 1, an isocyanate-terminated prepolymer was prepared according to the formulation shown in Table 2, and dimethylformamide (DMF) was added as a solvent to this to give a solid content of 50%. In addition, a chain extender listed in Table 2 was then added to obtain a polyurethane polymer. In Table 2, IPDI is isophorone diisocyanate, XDI is xylylene diisocyanate, IPDA is isophorone diamine, MOCA is 4,
4′-methylenebis(2-chloroaniline), MEA
is N-methyldiethanolamine, BG is 1,4
-Butanediol, HB represents 4,4'-bis(hydroxyethyl)bisphenol A. Example 1 To 100 parts of the polyurethane polymer solution (solvent, DMF, solid content 50%) obtained in Reference Example 1, 1 part of silicone surfactant and 45 parts of diluent (DMF) were added to prepare a coating mixture ( Viscosity 4300cps/10℃,
35% solids) and using the comma coater shown in Figure 1 as a continuous coating device,
It is continuously coated onto a release paper (PET film) that is fed out at a speed of 20 m/min so that the film thickness after drying is 20μ, and then passed through a drying oven maintained at 100℃ to dry (remain). 1 minute), then peel off the release paper and wind up the resulting continuous polyurethane film onto a winding roll. As a matter of course, the thickness of the film after drying can be set to 20μ by adjusting the clearance of the comma coater and adjusting the coating thickness of the compounded liquid. Incidentally, the coating thickness in this case was 0.07 mm. Method for measuring water absorption swelling rate and moisture permeability coefficient A solvent solution of polyurethane polymer is poured onto a glass plate, and the thickness is measured using a film applicator.
A film of 45μ, width 100mm, and length 150mm was obtained. 30
This film cut to mm width is marked with marked lines at 100 mm intervals, immersed in water at room temperature for 24 hours, then taken out of the water, the distance between the marked lines (l) is measured immediately after, and the value is calculated using the following formula. The water absorption swelling rate was calculated as the water absorption swelling rate. Water absorption swelling rate (%) = (l-100) x 100/100 The moisture permeability coefficient was measured according to the method of JIS Z-0208 using the film with a thickness of 45 μm obtained above.

【table】

【table】

[Table] As seen in Comparative Example 1 in Table 2, when the EO% in the final polyurethane polymer is as low as 15% or less, the moisture permeability of the film decreases, which is undesirable.
Furthermore, as seen in Comparative Example 2, when a PEG with a molecular weight of less than 200 is used, even if the water absorption swelling rate is 0, the moisture permeability of the film decreases, which is undesirable. If a PEG with a molecular weight exceeding 600 is used, although it has excellent moisture permeability, the water absorption swelling rate becomes extremely large, making it unsuitable for practical use. (Effects of the Invention) The moisture-permeable polyurethane film of the present invention is non-porous and has excellent physical properties, so there is no fear of tearing the film when peeling it from the release paper in the continuous manufacturing process, making it efficient. Stable operation is guaranteed, and depending on the application, it is possible to make the wall extremely thin, and the water absorption swelling rate is less than 15% (in many formulations it is virtually zero), which reduces the physical properties due to swelling when wet. This also suppresses deterioration, and even a film with a thickness of 20 μm, for example, can be obtained that is sufficiently durable for practical use. The ability to reduce the thickness in this manner is also favorable for moisture permeability. Further, even when water droplets adhere to a part of the film surface, no local blistering phenomenon is observed, and the film has excellent properties in terms of appearance quality. In particular, the moisture permeability coefficient measured for the 20μ product is 4500g/ ^m2・24H, which shows extremely good moisture permeability, making it a truly suitable material for materials such as moisture-permeable gloves and food packaging films. It is.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of an example of a continuous coating apparatus suitable for producing the polyurethane film of the present invention.

Claims (1)

[Claims] 1 Using a continuous coating device, apply a solvent solution of polyurethane polymer onto a release paper, then pass it through a drying oven to dry the solvent, and then
A continuous method for producing a polyurethane film comprising the step of winding up the formed film on a take-up roll without or without peeling it off from a release paper, the polyurethane polymer being polyethylene glycol with a molecular weight of 200 to 600 and an organic dicarboxylic acid. Alone or with an organic dicarboxylic acid and ε-caprolactone and/or
Or by reacting a short chain polyol, the polyoxyethylene content is 17-70% and the molecular weight is 500-3000.
a polyether-ester polyol, reacting the polyether-ester polyol with an organic polyisocyanate in the presence of a chain extender,
1. A method for producing a non-porous, moisture-permeable polyurethane film, comprising using a polyurethane polymer having a polyoxyethylene content in the range of 15 to 62% by weight.