JPH0674305B2 - Method for producing block copolymer containing polyvinyl ester polymer as one component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a block copolymer containing a polyvinyl ester polymer as a component. More specifically, it is represented by the general formula P · SH, where P includes the following structural units A and B, and B
Radical polymerization is possible in the presence of a polyvinyl ester-based polymer having a mercapto group only at the terminal whose content is more than 50 mol% and less than 100 mol% and the degree of polymerization is 3500 or less. The present invention relates to a process for producing a block copolymer containing a polyvinyl ester polymer as a component, which is characterized by radically polymerizing a monomer.

Block copolymers composed of bonds of polymer components having different properties have various different physical properties corresponding to the diversity of the copolymer components, and are used as impact-resistant resins, polymeric emulsifiers, dispersants, etc. In addition to its use, it has recently attracted attention as a membrane material and a medical material, and its research examples are wide-ranging along with the graft copolymer.

Regarding the polyvinyl ester-based polymer, much research and application have been conducted on the graft polymer having the polyvinyl ester-based polymer as a trunk or a branch, but a block copolymer containing the polyvinyl ester-based polymer as one component. There are few examples of. However, polyvinyl acetate and copolymers mainly composed of vinyl acetate are used, for example, as a shrinkage reducing agent for SMC, etc., because of their large interaction with various resins such as paints.

The present inventors have made use of these characteristics of a polyvinyl ester-based polymer centered on vinyl acetate, and have a polyvinyl ester-based polymer as one component as a means for making it possible to use the polyvinyl ester-based polymer in a wider range. As a result of earnestly studying the production method of the block copolymer,
Represented by the general formula P · SH, P contains the following structural units A and B, the content of B is 100 to 50 mol% (excluding 50 mol%), and the degree of polymerization is only 3500 or less (In the following explanation, "end" means "end only")
In the presence of a polyvinyl ester polymer having a mercapto group in the The inventors have found that a block copolymer having a polyvinyl ester polymer as one component can be produced by dicarpolymerization, and completed the present invention.

The polyvinyl ester-based polymer having a mercapto group at the terminal used in the present invention is a polyvinyl ester-based polymer obtained by polymerizing a vinyl monomer mainly composed of a vinyl ester monomer in the presence of thiol acid with ammonia or amine. Although it can be obtained by processing, the manufacturing method will be described in detail below.

First, the thiol acid used herein includes an organic thiol acid having a -COSH group. Examples thereof include thiol acetic acid, thiol propionic acid, thiol butyric acid, and thiol valeric acid. Among them, thiol acetic acid is most preferable because of its degradability.

As the vinyl ester, any vinyl ester capable of radical polymerization can be used. Examples thereof include vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl laurate, vinyl stearate and the like. Among them, vinyl acetate is preferable because it has the highest polymerizability and stability of ester bond. It is also possible to copolymerize the vinyl ester with a copolymerizable monomer. For example, ethylene, propylene, isobutylene, acrylic acid, methacrylic acid or salts thereof or alkyl esters thereof, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl-
(3-Acrylamido-3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether, N-vinyl pyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene and the like. .

Polymerization of vinyl monomers mainly composed of vinyl esters such as vinyl acetate in the presence of thiol acid of the present invention can be carried out in the presence of a radical polymerization initiator in any of bulk polymerization method, solution polymerization method, pearl polymerization method, emulsion polymerization method, etc. Although it can be carried out by a method, a solution polymerization method using methanol as a solvent is industrially most advantageous. The amount and method of addition of the thiol acid present during the polymerization to the polymerization system are not particularly limited and should be appropriately determined according to the physical properties of the intended polyvinyl ester polymer. As the polymerization method, a known method such as a batch method, a semi-continuous method, or a continuous method can be adopted.

As the radical polymerization initiator, known radical polymerization initiators such as 2,2′-azobisisobutyronitrile, benzoyl peroxide, and carbonate carbonate can be used, but 2,2′-azobisisobutyronitrile and the like can be used. Azo initiators are preferable because they are easy to handle. Initiating systems such as radiation and electron beams can also be used. The polymerization temperature is preferably selected from the range of 30 ° C to 90 ° C, though it is desirable to adopt an appropriate temperature depending on the kind of the initiator used. After polymerization for a predetermined period of time, unpolymerized vinyl esters are removed by a usual method to obtain a polyvinyl ester polymer having a thiolate ester group at the terminal. By reacting and decomposing amines such as ammonia in a polyvinyl ester polymer having a thiol ester group at the end, the thiol ester bond at the end is mainly decomposed without decomposing the ester bond in the main chain, and mercapto at the end. A vinyl ester-based polymer having a group can be obtained.

Various methods can be adopted for the catalytic reaction method of the polyvinyl ester-based polymer having a thiol ester group at the terminal and ammonia or amines, but it is preferable to react in a solvent that dissolves or swells the polyvinyl ester-based polymer. The reaction rate and selectivity are also good and preferred. For example, methanol, ethanol, acetone, dioxane, benzene, toluene and the like can be mentioned, but methanol is most preferable because it is industrially inexpensive, the reaction proceeds more smoothly, and is suitable as a polymerization solvent. As ammonia or amines, ammonia or alkylamines such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine and trimethylamine, alkanolamines such as ethanolamine, propanolamine and triisopropanolamine, fragrances such as aniline and dimethylaniline Although group amines and the like can be used, industrially, it is most advantageous to use ammonia in the form of aqueous ammonia, liquid or gaseous form.

The reaction temperature and time are appropriately determined depending on the type of amines used, but in order to more selectively decompose the thiol ester group at the terminal and decompose the ester bond in the main chain, the temperature and time should be unnecessarily high. It is desirable to avoid high temperature and long time. 20 ° C is the preferred temperature range
~ 60 ° C.

After completion of the reaction, it is desirable to take out the polymer by a non-solvent operation such as precipitation and separation, and further wash with a non-solvent such as water, or to dissolve the polymer in a solvent such as acetone and reprecipitate it in water for purification.

The method for producing a polyvinyl ester polymer having a mercapto group at the terminal used in the present invention has been described above. The degree of polymerization of this PVA polymer is 3500 or less, preferably 2
It is 000 or less, more preferably 1000 or less. Further, the content of B needs to exceed 50 mol%, and from the viewpoint of solubility in an organic solvent, it is preferably 70 mol% or more.

Next, a method for carrying out radical polymerization in the presence of a polyvinyl ester-based polymer having a mercapto group at the end of the present invention will be described.

As a polymerization method for achieving the object of the present invention, a generally known method such as bulk polymerization, solution polymerization, pearl polymerization and emulsion polymerization can be adopted. Further, as the polymerization process, any of a batch method, a semi-batch method and a continuous method can be adopted.

The radical polymerization for obtaining the block copolymer of the present invention is carried out by using a conventional radical polymerization initiator such as 2,2′-azobisisobutyronitrile, benzoyl peroxide, lauroyl peroxide, diisopropyl peroxycarbonate and the like. This is accomplished by using the one suitable for the polymerization system.

When radical polymerization is carried out in the presence of a polyvinyl ester polymer having a mercapto group at the end of the present invention, it is important and desirable that the polymerization system is acidic. This is because, when the mercapto group is basic, the rate at which it is ionically added to and disappeared from the double bond of the monomer is large, and the polymerization efficiency is significantly reduced.

The polymer constituting the other component of the block copolymer having the polyvinyl ester polymer of the present invention as one component is constituted by a homopolymer or a random copolymer of radically polymerizable monomers, and has a composition, a molecular weight, The molecular weight distribution is not particularly limited, but the weight ratio of the polyvinyl ester polymer and the other component polymer is preferably (weight of the other component polymer) /
(Polyvinyl ester polymer weight) = 0.1 to 20, more preferably (other component polymer weight) / (polyvinyl ester polymer weight) = 0.5 to 10.

In the present invention, the radical (co) polymerizable monomers include olefins such as ethylene, propylene and isobutylene, vinyl chloride, vinyl fluoride, vinylidene chloride, halogenated olefins such as vinylidene fluoride, vinyl formate, vinyl acetate and propionic acid. Vinyl, vinyl ester such as vinyl versatate, acrylic acid,
Methacrylic acid and its esters methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid 2-ethylhexyl, dodecyl methacrylate, methacrylic acid 2
-Hydroxyethyl, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate and quaternary products thereof, acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, acrylamido-2-methylpropanesulfonic acid and its sodium Examples thereof include acrylamide monomers of salts, styrene, α-methylstyrene, styrene monomers such as P-styrenesulfonic acid and its sodium and potassium salts, and N-vinylpyrrolidone.

The method for producing a block copolymer containing the polyvinyl alcohol polymer of the present invention as a component provides a method for producing a block copolymer containing a polyvinyl ester polymer having a very wide range of properties as a component. , The degree of polymerization of the polyvinyl ester having a mercapto group at the terminal, or the composition in the case of a copolymer is changed, and the composition and the molecular weight of the polymer of the other component are arbitrarily selected from the radical polymerizable monomer group and combined. It is achieved by

The block copolymer having the polyvinyl ester polymer as a component obtained in the present invention has a wide range of properties as described above, and further has a property different from that of the polymer blend, for example, a block copolymer. Since it has properties such as good compatibility between the polymer of one component and the polymer of the other component, film, molded article dispersant such as sheet, emulsifier, cement additive, ceramics, etc. It can be applied to a wide range of applications such as inorganic binders, adhesives and photosensitive resin materials.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. In the examples, parts and% mean weight basis.

[Synthesis of polyvinyl ester-based polymer having a mercapto group at the end]

(No.1) 2400 parts of vinyl acetate (hereinafter abbreviated as VAc), 580 parts of methanol and 0.93 parts of thiolacetic acid were placed in a reaction vessel, the inside was sufficiently replaced with nitrogen, and then the outside temperature was raised to 65 ° C and the inside temperature was changed to 60 ° C. After reaching ℃ 2,2'-azobisisobutyronitrile
20 parts of methanol containing 0.868 parts was added. Immediately thereafter, 60 parts of a methanol solution containing 17.4 parts of thiolacetic acid was uniformly added over 5 hours. The polymerization rate after 5 hours was 50.4%. After 5 hours, the vessel was cooled, and Vac remaining under reduced pressure was expelled together with methanol out of the evaporation system while adding methanol to obtain a PVAc methanol solution.
(Concentration 64.5%) Next, 31 g of this methanol solution was taken, 5 ml of 25% aqueous ammonia was added, and the mixture was stirred at 25 ° C for 10 minutes. Then, the mixture was poured into water to precipitate a polymer, and the reprecipitation operation was repeated twice with an acetone-water system for purification.

The polyvinyl acetate polymer thus obtained was measured by measuring [η] in acetone at 30 ° C. [η] = 7.94 × 10 ⁻³ ×
The degree of polymerization calculated by P- _0.62 was 125, the content of vinyl alcohol units determined from the degree of saponification was 10.2 mol%, and the content of vinyl acetate units was 89.8 mol%. The result of titration with iodine in a methanol / water (80/20 weight) system was 1.41 x 1
0 ^-4 presence mercapto group equivalent / g-PVAc was confirmed.
(No.2), (No.3) Polymerize by changing the amount of thiolacetic acid in the same manner as No.1,
PVAc was obtained. This was treated with 25% ammonia water to obtain PVAc having a mercapto group. The results are summarized in Table 1.

Toluene was added to 50 parts of the polyvinyl ester polymer of Example 1 (No. 1).
Dissolved in 280 parts, methyl methacrylate (abbreviated as MMA) 100
Parts were added and nitrogen substitution was carried out. The internal temperature rises to 80 ° C
At that point, 20 parts of toluene containing 0.3 part of 2,2'-azobisisobutyronitrile was replaced with nitrogen and then added. Polymerization was carried out for 5 hours to obtain a toluene solution of a block copolymer of polyvinyl ester and PMMA. Solids concentration is 32.7%
It was.

A 5% acetone solution of the polyvinyl ester-PMMA block copolymer obtained in Example 1 was cast to form a film. On the other hand, a 5% acetone solution of polyvinyl ester and PMMA having the same composition as this block copolymer was prepared and cast into a film. The film from the block copolymer was transparent and uniform, but the film from the mixture became cloudy and phase separation was observed.

Examples 2 to 6 Using the polyvinyl ester-based polymers of (No. 1) to (No. 3), polymerization was carried out in the same manner as in Example 1, and various blocks containing the polyvinyl ester-based polymer as one component. A polymer was obtained.
The results are summarized in Table 2.

However, in a system using methanol as the polymerization solvent, the polymerization temperature was 60 ° C.

Example 7 100 parts of distilled water was added to 0.1 part of PVA217 (polyvinyl alcohol; manufactured by Kuraray Co., Ltd., degree of polymerization 1700, degree of hydration 88 mol%),
It was melted at 90 ° C and cooled to 60 ° C under a stream of nitrogen. A styrene solution prepared by dissolving 50 parts of No. 2 polymer and 0.3 part of 2,2'-azobisisobutyronitrile in 100 parts of styrene was replaced with nitrogen, and then added to carry out rapid polymerization. Polymerization was carried out at 60 ° C for 20 hours, and the polymerization rate was 99.0%. After the termination of the polymerization, the polymer containing a block copolymer of polyvinyl ester-polystyrene by passing, washing with water and drying is used.
I got 4g.

Claims (2)

[Claims] 1. Represented by the general formula P.SH, P contains the following structural units A and B, the content of B is more than 50 mol% and 100 mol% or less, and the degree of polymerization thereof is 3500 or less. A process for producing a block copolymer comprising a polyvinyl ester polymer as one component, which comprises radically polymerizing a radically polymerizable monomer in the presence of a polyvinyl ester polymer having a mercapto group only at its terminal. (Here, R ¹ = H or a hydrocarbon group having 1 to 6 carbon atoms is represented, and R ² = H or a hydrocarbon group having 1 to 20 carbon atoms is represented.) 2. A process for producing a block copolymer according to claim 1, wherein R ¹ = H and R ² = CH ₃ .