JPS5964620A - Production of hydrophilic polyurethane foam - Google Patents

Abstract

PURPOSE:To produce a hydrophilic polyurethane foam having moderate water absorptivity, water retentivity and such flexibility as to permit heat processing and having widened use including toys, ladies' cosmetics, and washing tools by a one-shot process. CONSTITUTION:A flexible hydrophilic polyurethane foam is prepared by reacting a polyol with an organic polyisocyanate in the presence of a catalyst, a blowing agent, and other necessary additives. As the polyol component, there is used one comprising a copolymer of ethylene oxide with another epoxide having an average MW of 2,500-6,000, a content of ethylene oxide in the total epoxide of the polyol of 55-80wt% and an average functionality of 2.2-2.9. A hydroxyl group-containing polyoxyalkylene/siloxane copolymer soluble in the above polyol is used as a foam stabilizer, and the production is performed by a one-shot process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing flexible hydrophilic polyurethane foam by the Funshot method. In particular, the present invention relates to a method for producing a hydrophilic polyurethane foam that has appropriate water absorption and water retention properties and is flexible enough to be heat processed.

Conventionally, methods for producing flexible hydrophilic polyurethane foam include adding a water-absorbing polymer to flexible polyurethane foam, and using all polyols having hydrophilic groups using the Brepolymer method or Funschott method. However, these include the following problems. For example, regarding the method of adding water-absorbing polymer 'kk', JP-A-54-31199, JP-A-55-48
No. 223 discloses that polyurethane foam is produced by reacting an organic polyisocyanate and a polyol in the presence of a blowing agent and, if necessary, a catalyst and other auxiliaries. This is a polyurethane foam containing a water-absorbing polymer, characterized in that the above reaction is carried out by adding cellulose acrylic acid (salt) Gura 7Im combination.

This method works because the added water-absorbing polymer is solid7.
Difficult to uniformly disperse in the ohm 11. It had the disadvantage that it lacks hydrophilicity, resulting in some parts having poor hydrophilicity. In addition, water-absorbing polymers have poor heat resistance and may undergo thermal decomposition during heat processing, making them unsuitable for manufacturing secondary products that involve heat processing.

Next, regarding the prepolymer method, JP-A No. 49-69794
An example of the technology is disclosed in .

This method uses a prepolymer reacted with a polyol and an organic polyisocyanate with a high ethylene oxide content, but since a large amount of water is used, many urea bonds are formed, which inhibits hydrophilicity and increases water absorption. No hydrophilic polyurethane foam was obtained. Furthermore, the prepolymer method is disadvantageous in terms of economic efficiency due to the complicated process. Furthermore, regarding the one-shot method, Japanese Patent Publication No. 56-432471
C. An example of the technology is disclosed.

This method uses a bifunctional polyol containing 65 to 85 percent by weight of ethylene oxide to obtain a foam with high water absorption and volumetric swelling. However, it is very easily decomposed by heat, and the foam is destroyed when producing secondary products through heat processing, making it impossible to provide it for practical use.

The present invention solves the various drawbacks of these conventional methods, and is capable of heat processing, has appropriate water absorption and water retention properties even after heat processing, and has excellent foaming stability, that is, non-shrinkage and non-shrinkage. The object is to obtain a hydrophilic polyurethane foam having collapsible flexibility.

The method for producing flexible hydrophilic polyurethane foam of the present invention involves reacting a polyol with an organic polyisocyanate in the presence of a catalyst, a blowing agent, and other necessary additives. is in the range of 2500 to 6000, and the content of ethylene oxide in the total epoxide in the polyol is 55 to 8.
A polyol consisting of a copolymer of ethylene oxide and other epoxides with an average functional group number of 0% by weight and an average functional group number of 2.2 to 2.9 is used, and a hydroxyl group soluble in the polyol is added as a foam stabilizer. This is a method for producing a flexible hydrophilic polyurethane foam that can be heat-processed, characterized in that it is produced by a one-shot method using a polyoxyalkylene-siloxane copolymer having a polyoxyalkylene-siloxane copolymer.

In synthesizing the polyol used in the present invention, examples of initiators include glycols such as ethylene glycol, diethylene glycol, glopylene glycol, siglopylene glycol, butylene glycol, and hexylene glycol, chrycerin, and trimethylol. Triols such as propane, trimethylolethane and hexanetriol can be mentioned. The initiator may be a mixed initiator of diols and triols, or a single initiator. Other epoxides used in combination with ethylene oxide include propylene oxide, butylene oxide, and the like.

Furthermore, the polymerization of ethylene oxide and other epoxides may be either random copolymerization or block copolymerization. Note that the polyol having an average molecular weight of 25oO to 6,000 can be used, but if a polyol with an average molecular weight of less than 12,500 is used in the present invention, the resulting foam will have low mechanical strength and will have little utility value. Further, the average molecular weight of the polyol is 600.
If it exceeds 0, the foaming stability will be poor and it will be impractical.

Successfully produced hydrophilic polyurethane foam f that has appropriate water absorption and water retention properties and is heat processable by setting the number of functional groups of the polyol component in the range of 2.2 to 2.9. This is what I did.

Specifically, the number of functional groups of the polyol component is 2.
When set to 3, the ethylene oxide content needs to be at least 58% by weight, considering appropriate water absorption and water retention, and when the number of functional groups is set to 2.9,
The ethylene oxide content must be at least around 77% by weight.

Theoretically, if the number of functional groups in the polyol component is increased and the degree of crosslinking of the polyol is increased, the content of ethylene oxide in the total epoxide in the polyol is increased. It seems possible to produce a hydrophilic foam, but for those with a functional group number exceeding λ9, the acid content of ethylene oxide must be at least 80% by weight. However, it is not possible to obtain a normal communication form.In addition, the mechanical strength of the foam can be significantly improved by thermally processing the foam at a temperature in the range of 150°C to 250°C. I found 7.

As the number of functional groups in a polyol increases, it becomes necessary to perform heat processing at a higher temperature, but the greater the number of functional groups, the more remarkable the improvement in the mechanical strength of the foam before heat processing. In addition, we were able to find a material whose mechanical strength and water absorption can be improved through a thermal processing process.

As mentioned above, improvements in foam physical properties and water absorption properties have made it more advantageous to develop hydrophilic polyurethane foams into secondary processed products.

The foam stabilizer used in the present invention is a polyoxyalgylene-silokinane copolymer having a hydroxyl group that is soluble in the polyol component, and has the general formula [wherein R is ethylene oxide and oxidized Represents a propylene copolymer, X is 10 to 20
represents an integer of 3 to 10, and Y represents an integer of 3 to 10. However, the dimethylsiloxane group and the oxyalkylsiloxane group are randomly coordinated. ] For example, L-5340 [trade name of Nippon Unicar ■] and 5H-193 [trade name of )-Resilicone ■] can be mentioned. The silicone can be used in an amount of 0.2 to 3.0 parts based on 100 parts of polyol. If it is less than 0.2, the cell structure will become rough, and if it is further reduced, it will become difficult to form a shape, which may cause foam destruction. If the amount exceeds 3 parts, the proportion of closed cells in the foam will increase, and in extreme cases, it will lead to shrinkage foam.

Further, as the organic polyisocyanate used in the present invention, tolylene diisocyanate (TD Engineering) 2,4-isomer, 2,6-isomer, singly or in a mixture, and diphenylmethane diisocyanate can be used. As a catalyst, a tertiary amine and an organic tin compound can be used.

As a blowing agent, water or a low boiling point halogenated hydrocarbon can be used alone or in combination. It goes without saying that pigments and other additives can be used as necessary.

The hydrophilic polyurethane foam according to the present invention can be thermoformed at a temperature of 150°C to 250°C, as shown in the following examples, and the foam after thermoforming has a higher water absorption than the foam before thermoforming. The properties are improved by 4 to 28 times, and the physical properties are significantly improved with tensile strength of L4 to 21 and skin elongation of L5 to 4 times.

From the above, it can be seen that the flexible hydrophilic polyurethane foam obtained by the present invention has the following similarities with those produced by the conventional technology.

( ], ),; By making it possible to heat process and have water absorption and water retention of i degree, it will expand its application to secondary processed products and improve practical style (improvement of directivity). I ended up contributing a lot.

(2) In the manufacturing process of secondary processed products, the mechanical strength and water absorption properties of the foam can be significantly improved through thermal processing, and by selecting the thermal processing conditions, various quality requirements can be met. It has become possible to manufacture heat-processed secondary products according to the requirements.

The flexible hydrophilic polyurethane foam of the present invention can be used in toys, as well as conventional hydrophilic polyurethane foams.
Women's cosmetics, cleaning tools, mouthwash materials, f7? t4. It goes without saying that it can be used for purposes such as prevention systems and hydroponic culture media, and the range of applications has expanded to an extent that cannot be compared to conventional foam.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

(1) Synthesis of Polyol 1 Using ethylene glycol as an initiator, 50% by weight of ethylene oxide and 50% of propylene oxide were combined randomly with Versene 1 to obtain a bifunctional polyol with a molecular weight of 3000. Ta.

(2) Synthesis of Polyol I Using glycerin as an initiator, a trifunctional polyol having a molecular weight of 3,400 was obtained by random copolymerization of 80% by weight of ethylene oxide and 20% by weight of propylene oxide.

(3) Production of flexible hydrophilic foam from polyols I and (2) The blending ratio of polyols (1) and (2) was 70:30, and the average number of η functional groups was t2. The total amount of φ and the ethylene oxide content μ relative to the total epoxide in the polyol was adjusted to 58% by weight.

Polyol I 70 parts vertical polyol M 30 parts by weight water
2.5 heavy region triethylenediamine 0.10 TLkt part stannous octoate tJ, 15 fLIIn part L 534 f) [Nippon Unicar ■Product name: Average external molecular weight of R in the above general formula: 300-500 X: 11 ~16, Y:4~6
) O, s part TD In
dex 1
The ratio of the theoretical amount of polyincyanate required to react with all the active hydrogen compounds present in the 05 blue reaction mixture multiplied by 100 is expressed as Index.

Polyol in a 500-volume paper cup! Polyol #30 with a blending ratio of y r o of and polyol H of 30
Weighed 0 f'i, then added triethylenediamine dissolved in water, silicone L-5340 (foam stabilizer), and finally stannous octoate tank and after preliminary stirring, Index
TD Any 0 corresponding to 105 (blending ratio of 2,4-isomer and 2-6-isomer is 8:20) After stirring and mixing, the contents of the paper cup '1' become creamy and harden. At this point, the mixture is poured into a box made of silicone release paper to complete foaming.

Next, open at 90 to 100°C for about 30 minutes at 1:1
゛After completing ~, -radiate to the width of the room during the day and night, lG1. I. Cut to the size of a nova and measure the foam physical properties and thermal compression test, water absorption time, volume 1) Vg old rate using the following evaluation method.

0 Form evaluation method 1, Heat compression test Dry 2, OO, After setting the iron upper and F plates to the specified temperature with a spacer of 1 in between, the foam was placed between the upper and lower plates, heat compression was applied for 3 minutes, and the thickness of the foam after compression was determined according to JIIJK-6402. Measure the elongation rate and tensile strength of the foam using the same method. Thermoformability of foam (
Processability into various shapes through thermal compression process) and thermal deterioration status can all be confirmed.

2. Water absorption time: Place the dried 100 x 100 x 50% test piece on a horizontal table, and drop 1 d of water onto the surface of the foam using a syringe. The time required for water on the foam surface to be completely absorbed below the surface is expressed in seconds. The shorter the time it takes to absorb water, the more hydrophilic the polyurethane foam is.

8. Volume expansion rate Dry 200 x 200 x 50 test pieces are immersed in whole water, the volume after 8 hours is measured, and the ratio to the original test piece volume is expressed as a magnification.

The higher the magnification, the better the deep water resistance of the polyurethane foam.

The results of the evaluation test are shown in Table-1 and Table-2.

Example 2 All examples were the same except that the blending ratio of polyol ■ and polyol was adjusted to 'i30 near 0, the average number of functional groups was 2.7, and the content of ethylene oxide relative to the total epoxide in the polyol was adjusted to 1'y1 weight percent. This was done in the same manner as in step 1.

The results of the evaluation test are shown in Table-1 and Table-2.

Example 3 Polyol! The blending ratio of polyol I and polyol I is 90, the average number of functional groups is 2.9, and the content of ethylene oxide in the total epoxide in the polyol - Mouse? Everything was carried out in the same manner as in implementation v/11, except that 77% of heavy wages were used. ' The results of the first reviewer's test are shown in Table 1 and Table 2.

Comparative Example 1 All the same as Example 1 except that the blending ratio of polyol ■ and polyol n was 90:10, the average number of functional groups was 2.1, and the content of ethylene oxide was adjusted to 56 weight percent of the total epoxide in the polyol. I did the same thing.

The results of the evaluation test are shown in Table-1.

Example 4 (1) Synthesis of polyol (1) Using ethylene glycol as an initiator, a bifunctional polyol having a molecular weight of 5,000 was obtained by random copolymerization with an ethylene oxide content of 80% by weight and a propylene oxide content of 20% by weight.

(2) Synthesis of Polyol W Using glycerin as an initiator, 50% by weight of an ethylene oxide-containing column was copolymerized with a propylene oxide-containing column of 50% overlapping weight to obtain a trifunctional polyol having a molecular weight of 2SOO.

Everything was carried out in the same manner as in Example 1, except that the blending ratio of polyol ■ and polyol y was adjusted to 0:30, the average number of functional groups was adjusted to 265, and the content of ethylene oxide to the total epoxide in the polyol was adjusted to 71% by weight. Ta.

The results of the evaluation test are shown in Table-1 and Table-2.

Example 5 Blending ratio of polyol and polyol ■ + f: 30 near 0
The same procedure as in Example 1 was conducted except that the average number of functional groups was adjusted to 2.1 and the content of ethylene oxide relative to the total epoxide in the polyol was adjusted to 59% by weight.

The results of the evaluation test are shown in Table-1 and Table-2.

Comparative Example 2 Everything was the same as in Example 1, except that the total blending ratio of polyol and polyol W was 10:90, the average number of functional groups was -22h9, and the content of ethylene oxide in the total epoxide in the polyol was adjusted to i53% by weight. went.

The results of the evaluation test are shown in Table-1.

Comparative Example 3 All the same as in Example 1 except that the blending ratio of polyol ■ and polyol shoulder was 90=10, the average number of functional groups was 2, and the content of ethylene oxide relative to the total epoxide in the polyol was adjusted to 53 weight percent. I went to

The results of the evaluation test are shown in Table-1.

Comparative Example 4 All the same as Example 1 except that the blending ratio of polyol I and polyol ■ was 10:90, the average number of functional groups was adjusted to 2, and the total content of ethylene oxide to the total epoxide in the polyol was adjusted to 1% by weight. I did the same.

The results of the evaluation test are shown in Table-1.

17 Table-2 Elongation rate, tensile strength and water absorption time after thermal compression test Patent issue 1 person procedure amendment 111i fu 7ha+% 1. Oo 3 i, I
+9'0 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1°It f'l Indication Patent Application No. 57-175481 Title of Invention Process for Manufacturing Hydrophilic Polyurethane Foam 3 J City 11:
, to do - old things ('l relationship with Applicant (畢1 ['+0) Higashi 5; Page 4, lines 6 to 1 of the specification states that ``7 ohm failure occurred, making it impossible to provide a product for practical use''. "It was not something that could be used for applications that required physical strength."

(2) 1 line, page 10, Correct "Rin" to "Hi".

Same page 12, 4 lines, 10. Correct "8 parts" to "ro, sx quantity part".

, 7, page 12, line 15, Correct ``yari'' to ``yo''.

Claims (1)

[Claims] l) In order to produce a hydrophilic polyurethane foam having a flexible structure by reacting a polyol with an organic polyiso7anate in the presence of a catalyst, blowing agent and other necessary additives, the average molecular weight of the polyol component is 2500.
The content of ethylene oxide in the total epoxide in the polyol is in the range of 55 to 80 weight percent, and the average number of functional groups (degree of functionality) is in the range of 2.2 to 2.
．． It is produced by a one-shot method using a polyol consisting of a copolymer of ethylene oxide and other epoxides in the range of No. 9, and a polyoxyalkylene-siloxane copolymer containing hydroxyl soluble in the polyol as a foam stabilizer. 1. A method for producing a hydrophilic polyurethane foam having a flexible body that can be heat-processed.