JPH0441182B2 - - Google Patents

Description

[Detailed description of the invention]

A. Technical Field of the Invention The present invention relates to novel polymeric compositions. More specifically, water-soluble or water-dispersible block copolymers containing a polyvinyl alcohol polymer as one component and a polymer having an ionic group as the other component, and water-soluble or water-dispersible proteins (excluding gelatin) The present invention relates to a polymer composition characterized by containing the following. In particular, water-soluble or water-dispersible block copolymers containing a polyvinyl alcohol polymer as one component and a polymer having an ionic group as the other component, and water-soluble or water-dispersible proteins (excluding gelatin)
The present invention relates to a polymer composition which is characterized by containing the following, and which has improved the disadvantages of protein (excluding gelatin) films such as brittleness and weakness and "stickiness" due to moisture absorption. B. Prior art and its problems Among water-soluble polymers, polyvinyl alcohol polymers (hereinafter abbreviated as PVA polymers) have particularly excellent protective colloid ability and film strength properties, and are widely used in many fields. As is well known, PVA-based polymers can be used alone or in combination with other water-soluble or water-dispersible polymeric substances such as starches, cellulose derivatives such as hydroxyethyl cellulose, proteins such as casein, and latexes such as SBR. In many cases, therefore
The compatibility between the PVA polymer and these water-soluble or water-dispersible polymer substances is an extremely important issue in order to fully exhibit the excellent properties of the PVA polymer in the above-mentioned combination system. However, compatibility between different types of polymers is generally poor, and even for PVA-based polymers,
Despite various attempts to improve compatibility (for example, Japanese Patent Publication No. 56-14544, Japanese Patent Publication No. 56-55440, and Japanese Patent Publication No. 54-133543), the compatibility with the above-mentioned water-soluble or water-dispersible polymers is poor. Currently, the compatibility with proteins such as casein is particularly poor. C Structure, purpose, and effect of the present invention As a result of intensive studies in view of the above circumstances, the present inventors have found that a water-soluble or water-dispersible product containing a PVA-based polymer as one component and a polymer having an ionic group as the other component. The present invention was completed based on the discovery that a polyester block copolymer is well compatible with water-soluble or water-dispersible proteins (excluding gelatin) and provides a film with good transparency. A water-soluble or water-dispersible block copolymer containing the PVA-based polymer of the present invention as one component and a polymer having an ionic group as another component is a water-soluble or water-dispersible block copolymer containing a water-soluble or water-dispersible protein (excluding gelatin). The reason for the good compatibility with the block copolymer is due to the electrostatic interaction between the ionic groups of amino acid residues in these proteins (excluding gelatin) and the ionic groups in the block copolymer.
This is thought to be due to improved compatibility between the PVA polymer portion and these proteins. D More detailed description of the present invention PVA forming a component of the polymer composition of the present invention
A water-soluble or water-dispersible block copolymer containing a polymer as one component and a polymer having an ionic group as another component can be produced by various arbitrary methods; As shown in the example, in the presence of a PVA polymer having a mercapto group at the end obtained by saponifying a polyvinyl ester polymer having a thiol acid ester group at the end, a radically polymerizable ionic group is added. The most preferable method is to radically polymerize monomers having the above-mentioned properties. (Japanese Patent Application No. 58-61746, Japanese Patent Application No. 58-52673) The detailed method is described below. First of all, it has a mercapto group at the end.
The PVA-based polymer is obtained by saponifying a polyvinyl ester-based polymer obtained by polymerizing vinyl monomers mainly composed of vinyl ester monomers in the presence of thiol acid by a conventional method. The thiol acids used herein include organic thiol acids having a -COSH group. Examples include thiol acetic acid, thiol propionic acid, thiol butyric acid, and thiol valeric acid, among which thiol acetic acid is the most preferred because of its good degradability. Furthermore, any vinyl ester that can be radically polymerized can be used. Examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl laurate, vinyl stearate, etc. Among them, vinyl acetate has the best polymerizability and is preferred. Polymerization of vinyl monomers mainly consisting of vinyl esters such as vinyl acetate in the presence of thiol acid can be carried out by any method such as bulk polymerization, solution polymerization, pearl polymerization, or emulsion polymerization in the presence of a radical polymerization initiator. However, solution polymerization using methanol as a solvent is industrially most advantageous.
There are no particular limitations on the amount of thiol acid added to the polymerization system and the method of addition, which should be appropriately determined depending on the intended physical properties of the polyvinyl alcohol polymer. As the polymerization method, known methods such as a batch method, a semi-continuous method, and a continuous method can be employed. As the radical polymerization initiator, known radical polymerization initiators such as 2,2'-azobisimptilonitrile, benzoyl peroxide, and carbonate peroxide can be used, but azo-based radical polymerization initiators such as 2,2'-azobisisobutyronitrile can be used. Initiators are preferred because they are easy to handle. Furthermore, radiation, electron beams, etc. can also be used. It is desirable to select an appropriate polymerization temperature depending on the type of initiator used, but it is usually selected from the range of 30 to 90°. After polymerization for a predetermined period of time, unpolymerized vinyl esters are removed by a conventional method to obtain a polyvinyl ester polymer having a thiol acid ester group at the end. The polyvinyl ester polymer thus obtained is saponified by conventional methods, but it is usually advantageous to prepare the copolymer as an alcohol solution, particularly a methanol solution. Not only anhydrous alcohols but also those containing a small amount of water can be used depending on the purpose, and organic solvents such as methyl acetate and ethyl acetate may be optionally contained. The saponification temperature is usually selected from the range of 10 to 70°C. The saponification catalyst is preferably an alkaline catalyst such as sodium hydroxide, potassium hydroxide, sodium methylate, potassium methylate, etc. The amount of the catalyst to be used is appropriately determined depending on the degree of saponification and water content, etc. It is desirable to use a molar ratio of 0.001 or more, preferably 0.002 or more.
On the other hand, if the amount of alkali is too large, it will be difficult to remove the residual alkali from the polymer, and the polymer will be colored, which is undesirable.
It is desirable to do the following. Through this saponification reaction, the terminal thiol acid ester and the vinyl ester bond in the main chain of the polyvinylethesyl polymer having a thiol acid ester group at the terminal are saponified, and the polymer terminal becomes a mercapto group and the main chain becomes vinyl alcohol. The degree of saponification of the vinyl ester unit in the main chain can be changed depending on the purpose of use, but it is 20 mol% or more, preferably 50 mol%.
There is no particular restriction as long as it is above, more preferably 70 mol% or more. The polymer precipitated after the saponification reaction is purified by a known method, such as washing with methanol, to remove impurities such as residual alkali and alkali metal salts of acetic acid, and then dried to obtain a white powder. Next, a method for radical polymerization of a monomer having an ionic group in the presence of a PVA polymer having a mercapto group at the end will be described. As the polymerization method, generally known methods such as bulk polymerization, solution polymerization, pearl polymerization, and emulsion polymerization can be adopted, but a solvent that can dissolve the PVA polymer, such as a medium mainly composed of water or dimethyl sulfoxide, can be used. Preferably, the polymerization is carried out in. Further, as the polymerization process, any of a batch method, a semi-batch method, and a continuous method can be adopted. Radical polymerization to obtain a block copolymer is carried out using a conventional radical polymerization initiator, such as 2,
This can be achieved by using one suitable for the polymerization system from among 2'-azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, diisopropyl peroxycarbonate, potassium persulfate, ammonium persulfate, etc. However, in the case of polymerization in an aqueous system, it is also possible to initiate redox using the mercapto group at the end of PVA and an oxidizing agent such as potassium bromate, potassium persulfate, ammonium persulfate, or hydrogen peroxide. Under polymerization conditions, PVA alone does not generate radicals, but decomposes and generates radicals only through redox reaction with the mercapto group at the end of PVA. It is a drug. When performing radical polymerization in the presence of the PVA polymer having a mercapto group at the terminal of the present invention,
It is important and desirable that the polymerization system is acidic. This is because when the mercapto group is basic,
This is because the rate at which monomers ionically add to and disappear from double bonds is high, resulting in a significant drop in polymerization efficiency.
It is desirable to conduct the test at pH 4 or lower. The PVA polymer referred to in the present invention is
It refers to a polymer containing 20 mol% or more, preferably 50 mol% or more, more preferably 70 mol% or more of vinyl alcohol units, and other monomer components include vinyl acetate, vinyl formate, propionic acid, etc. Vinyl, vinyl versatate, ethylene, propylene, (meth)acrylic acid and its salts, itaconic acid, maleic acid, fumaric acid and their salts, 2-acrylamidopropanesulfonic acid and its salts, (meth)acrylamidopropyltrimethylammonium chloride There is nothing wrong with including such things. The degree of polymerization is not particularly limited as long as it is in the range of 10 or more and 3500 or less. It is one component of the polymer composition of the present invention. PVA
Regarding water-soluble or water-dispersible block copolymers that contain a PVA-based polymer as one component and a polymer with an ionic group as another component, other components other than the PVA-based polymer component must contain ionic groups. There is no particular restriction as long as the polymer is a radical (co)polymerizable ionic monomer, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, vinyl sulfuric acid, vinyl sulfonic acid, P-styrene sulfonic acid. , 2-acrylamidopropanesulfonic acid, 2-acryloyloxyethyl phosphoric acid, etc., and anionic monomers such as their metal salts and ammonium salts, and cationic monomers such as dimethylaminoethyl (meth)acrylate and (meth)acrylamidopropyltrimethylammonium chloride. Homopolymers or copolymers of monomers, or the above ionic monomers and acrylamide, methacrylamide, N,N-dimethylacrylamide, N-vinylpyrrolidone, methyl (meth)acrylate, ethyl (meth)acrylate, (meth) It is composed of a copolymer of radical (co)polymerizable nonionic monomers such as acrylonitrile, ethylene, and propylene. Among the above radical (co)polymerizable ionic monomers, monomers containing carboxyl groups (including metal salts and ammonium salts) such as acrylic acid and methacrylic acid, vinyl sulfonic acid, P-styrene sulfonic acid, 2 - Monomers containing sulfonic acid groups (including metal salts and ammonium salts) such as acrylamide propane sulfonic acid, and nonionic monomers that can be copolymerized with these ionic monomers, especially acrylamide, methacrylamide, N, N-dimethylacrylamide, N-vinylpyrrolidone and the like are preferred as monomers constituting the ionic polymer. In addition, the amount of ionic groups in the ionic polymer is 0.5 mol% or more, preferably 1 mol% because it interacts with water-soluble or water-dispersible proteins (excluding gelatin).
The content is more preferably 2 mol% or more. The weight ratio between the PVA polymer component and the other ionic polymer component in the block copolymer is not particularly limited, but 0.2≦(PVA polymer)/(ionic polymer)≦
50 More preferably, 0.3≦(PVA polymer)/(ionic polymer)≦
When the molecular weight is 40, a polymer composition which has excellent compatibility with water-soluble or water-dispersible proteins (excluding gelatin) and which is the object of the present invention can be obtained. Examples of water-soluble or water-dispersible proteins (excluding gelatin) in the present invention include casein, albumin, and modified products thereof. When used as a fiber treatment agent, casein is particularly preferred as a water-soluble or water-dispersible protein (excluding gelatin). The composition of the polymer composition of the present invention is not particularly limited other than that it contains a water-soluble or water-dispersible protein (excluding gelatin) and the block copolymer described above, and may be varied depending on the various intended uses described above. However, it is particularly desirable that the weight mixing ratio of the water-soluble or water-dispersible protein (excluding gelatin) and the block copolymer is the former/latter = 10/90 to 99/1. Particularly preferred is the former/latter ratio of 20/80 to 90/10. Further, there is no problem in containing polyvinyl alcohol or other water-soluble polymers other than the block copolymer component as long as the object of the present invention is achieved without impairing compatibility. The present invention will be described in detail below with reference to Examples. In addition, both "%" and "part" in the examples indicate "% by weight" and "part by weight". Preparation of block copolymer Polyvinyl alcohol having a mercapto group at the end (degree of saponification = 98.7 mol%, [HS] = 1.46 × 10 ^-5
Add 420 parts of distilled water to 100 parts of eq/g), dissolve by boiling, cool to room temperature, and adjust the pH with 1N-H ₂ SO ₄ .
Adjusted to 3.0. Next, 10 parts of acrylic acid monomer was added and dissolved, and after nitrogen substitution, the temperature was raised to 70°C, and an aqueous initiator solution containing 0.38 parts of K ₂ S ₂ O ₈ dissolved in 20 parts of distilled water was added to initiate polymerization. It started. 3 hours, 70
After stirring and polymerizing at .degree. C., the mixture was cooled to room temperature to obtain an aqueous polyvinyl alcohol-polyacrylic acid block copolymer solution. Adjust pH to 5.5, concentration is 17.3%
It was hot. Moreover, the viscosity at 20°C was 4500 cp.
This block copolymer is referred to as block copolymer A. Block copolymers B to M were prepared in the same manner. The composition and concentration pH are summarized in Table 1.

[Table] Examples 1 to 7 and Comparative Examples 1 to 6 Properties of films obtained by casting polymer compositions 5% ammoniacal aqueous solution of casein (reagent manufactured by Hanui Chemical Co., Ltd.) Mix equal amounts of a 5% aqueous solution of a polyester polymer at 50℃, stir thoroughly at 80℃, and then spread it on a polyester film in a thick layer.
Casting was carried out to obtain a film of 20 μm, and the film was air-dried at room temperature. Compatibility was determined by observing the presence or absence of phase separation and transparency of the obtained film. The results are summarized in Table 2. Evaluation was made on a three-grade scale: ○ means completely transparent, △ means slightly cloudy, and × means phase separation.

【table】

[Table] As is clear from Table 2, the water-soluble polymer mixed with casein contains PVA polymer as one component,
Only when the copolymer is a water-soluble or water-dispersible block copolymer containing a polymer having an ionic group as another component, the obtained film has good transparency and good compatibility.

Claims (1)

[Scope of Claims] 1. A water-soluble or water-dispersible block copolymer containing a polyvinyl alcohol-based polymer as one component and a polymer having an ionic group as another component, and a water-soluble or water-dispersible protein ( (excluding gelatin). 2 The ionic group of the polymer having an ionic group is
The polymer composition according to claim 1, which is an anionic group. 3 The ionic group of the polymer having an ionic group is
The polymer composition according to claim 1, which is a cationic group. 4 Claim 1 in which the content of ionic groups in the polymer having ionic groups is 0.5 mol% or more
The polymer composition described in . 5. The polymer composition according to claim 1, wherein the water-soluble or water-dispersible protein (excluding gelatin) is casein.