JP3061853B2 - Porous acrylic film - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a porous acrylic film useful as a film having water retention and waterproof / moisture permeability.

(Prior art)

Acrylic polymer film (hereinafter referred to as acrylic film), which is a copolymer containing acrylic acid ester and / or methacrylic acid ester as a main component, has excellent properties such as transparency, weather resistance, and water resistance. Because it has the feature that the feel can be freely adjusted from hard to soft by changing it, it can be used as a single film or as a laminate with other materials, and as a coating applied to various substrates Widely used. As a material in which pores are generated in an acrylic polymer, foams of an acrylic polymer have been conventionally known. For example, a foam or sheet obtained by foaming an acrylic polymer containing methyl methacrylate as a main component using a foaming agent or an emulsion of an acrylic polymer (hereinafter referred to as an acrylic emulsion) is vigorously stirred and foamed, and then cast. Foams obtained by molding are known.

[Problems of the prior art and problems to be solved by the present invention]

The foam obtained by the above-mentioned known technique generally has a large pore diameter of several hundred μm to several mm, and has a high expansion ratio of several to several tens times, and pores are present in the polymer film. Rather, the polymer thin film has a form in which a large number of pores are formed, and no longer has the properties of the acrylic polymer used as the raw material. Such an acrylic polymer foam is suitable for application as a plastic foam or acrylic leather, and has both waterproofness and moisture permeability as the object of the present invention, and as a film excellent in water retention. Is not suitable. Thus, the average diameter is 0.
An acrylic film having pores of 001 to 50 μm and having a pore volume of 0.0010 to 0.0500 cm ³ / g has not existed conventionally, and the present invention maintains the original properties as an acrylic polymer while maintaining the original properties. Another object of the present invention is to provide a novel porous acrylic film provided with waterproof / moisture permeability and water retention.

[Means for achieving the task]

The present inventors have found that a film in which pores having a specific average diameter are present in an acrylic polymer film with a specific pore volume can achieve the above object, and have reached the present invention. .

That is, the present invention is a film substantially composed of an acrylic polymer, wherein the film has an average diameter of 0.001 to 50.
The present invention relates to a porous acrylic film having pores having a thickness of μm and a pore volume ratio of 0.0010 to 0.0500 cm ³ / g.

The acrylic polymer in the present invention is a polymer obtained by using only a known acrylic acid ester and a copolymer of acrylic ester and / or methacrylic acid ester and other monomers, and includes acrylic acid ester and / or Alternatively, it refers to a copolymer obtained by using an acrylate ester in a proportion of 30% by weight or more of all monomer components. More preferable acrylic polymer, acrylic acid or methacrylic acid and an aliphatic alcohol having 1 to 22 carbon atoms,
It is a copolymer containing at least one of the esters of alicyclic alcohols in a proportion of 50% by weight or more of the total monomers.

 Acrylic polymer is in the form of a lump or organic solvent
Or a dispersion, an aqueous solution or an aqueous dispersion.
However, the porous acrylic film of the present invention can be used to remove starch.
When obtained by leaving, it is easy to mix with starch,
Easy to obtain a film in which starch is uniformly dispersed
From the advantages of health, safety, price, and ease of handling
Preferably in the form of an aqueous solution or dispersion,
Because of the excellent performance of the obtained film, an aqueous dispersion
It is particularly preferred that the form is Specifically acrylic
With emulsion or styrene acrylic emulsion
Products marketed as 202E,
Ack reset 204E, Ack Reset 210E, ACRISSET
G 285E, Ack Reset 110E (both from Nippon Shokubai Chemical
Industrial Co., Ltd.) can be preferably used.
Also, these acrylic emulsions can be used
Melamine resin or epoxy resin
You can do it.

The porous acrylic film of the present invention has an average diameter of 0.001 to 50 μm, preferably 0.001 μm, in the acrylic polymer film.
Voids of 空 20 μm are included in a pore volume range of 0.0010-0.0500 cm ³ / g. As a means for forming pores, for example, there is a method in which the following additives are mixed into an acrylic polymer to form a film, and then the additives are removed.

Additive Solvent incompatible with acrylic polymer Dye Water-extractable substance Among the above-mentioned additives, the water-extractable substance is easy to adjust the diameter of pores to be formed, and is an extract for removing the additive. This is preferable because water can be used as a medium for the above. As the water-extractable substance, a natural or synthetic water-soluble or water-dispersible polymer compound can be preferably used, but starch having a particle diameter suitable for the film of the present invention, inexpensive, and easy to handle is preferably used. Particularly preferred.

Hereinafter, a method for producing the porous acrylic film of the present invention using starch will be described.

Starch is, for example, rice, barley, wheat, corn, sweet potato, potato, kuzu, azuki, lotus,
Known materials such as starch obtained from buckwheat and millet can be used. These starches may be processed by partial decomposition, cationization and the like. Since the pore size of the obtained porous acrylic film depends on the particle size of the starch to be used, a starch is selected and used so as to obtain a pore size suitable for the use of the porous acrylic film. The relationship between the type of starch and the pore size is, for example, as follows. Potato starch; about 15-20 microns, corn starch; 8-12
Micron, rice starch; 1-10 microns, soluble starch; 1-1000 angstroms.

The ratio between the acrylic polymer and the starch is adjusted so that the pore volume of the porous acrylic film is in the range of 0.0010 to 0.0500 cm ³ / g.
The starch solids weight ratio should be in the range of 100/1 to 100/200,
From the viewpoint of the strength and performance of the obtained film, 100/10 ~
More preferably, it is in the range of 100/100. Starch may be used in any form of powder, paste, dispersion, and aqueous solution. The solvent when used in the form of a paste or a dispersion can be water or an organic solvent.

The acrylic polymer and starch are mixed at a predetermined ratio and stirred to form a uniform mixture, and a film is formed from this mixture. The film can be prepared by a known method such as a melt extrusion method or a casting method. However, when the acrylic polymer is in the form of an aqueous solution or a water dispersion, the casting method is convenient.

The thickness of the film is not particularly limited, but is suitably in the range of 10 μm to 1 mm.

In order to extract starch from an acrylic polymer film, for example, an acrylic polymer film containing starch may be swollen in boiling water and then decomposed in dilute sulfuric acid to generate voids. However, in this method, when the acrylic polymer film is in the form of an aqueous dispersion, there is a tendency that the acrylic polymer is deteriorated or deteriorated by the treatment depending on the polymer component.
Therefore, the present inventors examined this point, and found that if the starch is removed by a starch-degrading enzyme, the treatment can be performed under mild conditions, so that the polymer does not deteriorate and a porous acrylic film with excellent performance can be obtained. Was.
That is, a preferred embodiment of the method for producing a porous acrylic film of the present invention is an acrylic polymer and starch, or a mixture of starch and starch-degrading enzyme to obtain an acrylic polymer containing starch. Is formed into a film, and then the starch is removed from the film by an amylolytic enzyme to form pores.

There are various amylases as amylolytic enzymes,
Specific examples include α-amylase, β-amylase, isoamylase, pullulase, glucoamylase and the like. Among them, glucoamylase is more preferable because it can efficiently remove starch under mild conditions. There are the following two methods for removing starch from an acrylic polymer film containing starch.

A method in which an acrylic polymer film containing starch is contacted with an aqueous solution of a starch-degrading enzyme to hydrolyze and extract the starch.

A method in which starch and an amylolytic enzyme are mixed into a polymer to form an acrylic polymer film having starch therein, and this is contacted with water to hydrolyze and extract the starch to remove it.

The concentration of the aqueous solution of amylolytic enzyme is in the range of 0.1 to 100 g /, preferably 0.5 to 10 g /. The ratio of starch to amylolytic enzyme used is in the range of starch / amylolytic enzyme = 100 / 0.1 to 100/20, preferably 100
The range is from / 1 to 100/10.

The temperature at which starch is removed in either method is
It can be in the range of 10-100 ° C, but preferably 40
~ 80 ° C, and the time may be determined so that the degree of starch removal is the desired degree, and is generally
The range is from 10 minutes to 72 hours, preferably from 12 to 48 hours.

Acrylic film and porous acrylic film in the present invention, not only refers to the film alone, the film and other plastic film, cloth, paper,
Base materials such as coatings, fabrics, papers, etc. obtained by applying a mixture of polymer and starch to a metal plate, a product obtained by laminating an inorganic base material such as a slate board, plastic, cloth, paper, metal, wood, or an inorganic base material and drying. It includes an impregnated product obtained by impregnating and drying a mixture of a polymer and starch into a material, and a film reinforced with glass fibers, metal fibers, and organic fibers.

The porous acrylic film of the present invention thus obtained has micropores uniformly distributed in the film, and it is probably due to the fact that even when the starch is decomposed and extracted by 100%, a small amount of starch is derived from the remaining starch. It has excellent hydrophilicity which is considered to be there. For this purpose, the porous acrylic film of the present invention has an equilibrium moisture absorption of 3.5% at 100% RH.
It has a moisture permeability of 11 to 100 g / 24 hr / m ² / mm at RH of 30%, more preferably 3.5 to 20%, and 100% RH, and has a tensile strength of 5 kg / cm ² or more. That is, the film of the present invention is excellent in strength, water retention and waterproof / moisture permeability. By utilizing its properties, it is possible to coat dew condensation preventing wall materials, moisture permeable and waterproof clothing materials, and various base materials. It is useful as an agent, adhesive or impregnating agent.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.
Unless otherwise specified, "part" indicates "part by weight" and "%" indicates "% by weight".

Example 1 (Preparation of starch-containing acrylic film) 204E (Nippon Shokubai Chemical Co., Ltd.
Krill emulsion, solid content 49%) 10 parts rice star
3 parts were added to obtain a uniform mixture. Release the mixture to release paper
And then dried at room temperature.
A 200 μm film was obtained.

(Preparation of starch decomposing solution) AMG (manufactured by NOVO INDUSTRI A / S,
Glucoamylase) and 1 part of AMG with 0.1M citric acid
The mixture was dissolved in 1000 parts by volume of a buffer adjusted to pH 4.5 by mixing 0.2 M sodium monohydrogen phosphate.

(Hydrolysis of Starch) The film was immersed in a starch decomposition solution adjusted to 60 ° C. for 18 hours.

(Measurement of hydrolysis rate) The produced glucose was measured by a modified somology method,
The hydrolysis rate was calculated. 70.2% of the starch used was hydrolyzed.

(Measurement of Void Volume) A sample (film) suspended from a precision balance with a thin steel wire is immersed in n-heptane, and the weight is measured every minute, and the time obtained from the relationship diagram between the elapsed time and the weight 0 The apparent specific volume was calculated from the extrapolated value to the following equation.

On the other hand, n-heptane in which the sample was immersed was degassed under reduced pressure in a desiccator. Thereafter, the sample weight was measured in n-heptane, and the true specific volume was calculated from the following equation.

Next, the pore volume was calculated by the following equation.

Pore volume = apparent specific volume - True specific volume (cm ³ / g) pore volume was 0.0079cm ³ / g.

(Confirmation of Void Formation by Electron Microscope) The film in the example was observed with an electron microscope.
Was. Ack reset without using starch Use 204E alone
No pores were observed in the film obtained. De
Contains starch before treatment with aqueous amylolytic enzyme
Acrylic polymer film
It is confirmed that starch particles are dispersed in the
Came. Acrylic polymer film containing starch
Immersed in an aqueous amylolytic enzyme solution for 18 hours
In a porous film, the starch is hydrolyzed to form a porous film.
It was confirmed that the film was generated. The hole diameter of the hole
Was found to be approximately in the range of 3 to 6 μm.

Examples 2 to 15 The same operation as in Example 1 was repeated except that the polymer, starch, starch-degrading enzyme, starch-degrading treatment conditions and the like were as shown in Table 1, to obtain a porous film.

Comparative Example 1 Example 1 except that AMG (glucoamylase) was not used.
The same operation was repeated to prepare a film for comparison.

Starch hydrolysis rate 1.3%, pore volume 0.0009cm ³
/ g.

(Note 1) AMG: Similar to Example 1, 0.1 M citric acid and 0.2 M sodium monohydrogen phosphate were mixed and dissolved in a buffer adjusted to pH 4.5.

(Note 2) BAN; manufactured by NOVO INDUSTRI A / S, α-amylase 0.1 M citric acid and 0.2 M sodium monohydrogen phosphate were mixed and dissolved in a buffer adjusted to pH 6.0.

(Note 3) Acrylic 285E; Nippon Shokubai Chemical Industry Co., Ltd.
Acrylic Emulsion M-3; Sumitex Resin M-3; Sumitomo Chemical Co., Ltd.
Melamine resin Acrylic 285E / M-3 = 100/5 (solid content ratio). After preparing a starch-containing acrylic film at room temperature, a heat treatment was performed at 120 ° C. for 5 minutes.

(Note 4) Arolon 453; water soluble by Nippon Shokubai Chemical Industry Co., Ltd.
Acrylic resin Non-volatile content 50% (Note 5) Alloset 5270;
Acrylic resin 40% non-volatile content Example 16 Acryset Rice starch 3 parts and AM in 10 parts of 204E
G 0.15 parts was added to obtain a uniform mixture. Release the mixture
After coating on paper and drying at room temperature, remove the release paper
A film of about 200 μm was obtained.

(Hydrolysis of Starch) A buffer adjusted to pH 4.5 by mixing 0.1 M citric acid and 0.2 M sodium monohydrogen phosphate was adjusted to 60 ° C., and the film was immersed in this for 18 hours. .

Hydrolysis rate is 75.3% and pore volume is 0.0081cm ³ / g
Met.

Examples 17 to 19 Except that the polymer, starch, amylolytic enzyme and amylolytic conditions were as shown in Table 2
The same operation as in step 16 was repeated to obtain a porous film.

Comparative Example 2 Acryset 285E / M-3 Ammonium stearate was added to 10 parts.
0.3 part was added, and the mixture was stirred at a high speed with a homomixer and foamed until the volume was doubled, and then cast on release paper. After preheating this at 80 ° C for 15 minutes, heat it at 120 ° C for 5 minutes,
A foam sheet having a thickness of about 500 μm was obtained. Observation of the sheet with an optical microscope revealed that the size of the bubbles (voids) was in the range of 0.5 to 1 mm.

Example 20 For each of the films obtained in Examples 1 to 19 and Comparative Examples 1 and 2 and the non-porous acrylic film, the equilibrium moisture absorption, water vapor transmission and film properties (elongation, strength) at each temperature were measured. It was measured. The measuring method of each item is as follows.

(Equilibrium moisture absorption) Put the sample (film) in a desiccator containing a water / glycerin mixture in a ratio that will give a specified humidity,
After 48 hours, the weight (Wwet) was measured, and then the sample was
The weight (Wdry) after drying at 5 ° C. for 2 hours was measured, and the equilibrium moisture absorption was measured by the following equation.

(Moisture Permeability) Place a cup containing calcium chloride in a desiccator containing a water / glycerin mixture in a ratio such that a predetermined humidity is achieved, and tightly seal with a sample (film). After elapse of 24 hours at 20 ° C, calcium chloride Was measured for weight increase.

(Film properties) Samples were taken at 20 ° C and 65% R using an Instron universal testing machine.
A tensile test was performed under the condition of H.

 Table 3 shows the measurement results of each item.

Continuation of front page (56) References JP-A-2-18429 (JP, A) JP-A-63-75043 (JP, A) JP-A-62-250002 (JP, A) JP-A-52-135358 (JP, A) JP-A-3-223350 (JP, A) JP-B-43-6149 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/00-9/42

Claims (3)

(57) [Claims] 1. A film substantially composed of an acrylic polymer, wherein pores having an average diameter of 0.01 to 50 μm are intrinsically present in the film in a pore volume range of 0.0010 to 0.0500 cm ³ / g. Porous acrylic film. 2. An acrylic polymer obtained by radical polymerization of a monomer component containing 30 to 100% by weight of an acrylate and / or methacrylate having an alkyl group having 1 to 22 carbon atoms. Certain claim 1
The porous acrylic film according to the above. 3. The porous acrylic film according to claim 1, wherein the pores are generated by removing starch contained in the film.