JPH02202920A - Modified polyvinyl alcohol graft terpolymer - Google Patents

Abstract

PURPOSE: To obtain a modified polyvinyl-alcohol-grafted terpolymer having improved heat resistance by esterifying the hydroxyl groups of a PVA with the acid anhydride groups of a specified acrylate/maleic anhydride copolymer through ring opening to graft the copolymer onto the PVA.

CONSTITUTION: 30-70 wt.% random acrylate/maleic anhydride copolymer represented by formula I (wherein R is H or methyl; R¹ is a 1-4C saturated alkyl; m is 30-90 mol% and n is 70-10 mol%) is dissolved in e.g. dimethyl sulfoxide, and the formed solution is mixed with 70-30 wt.% PVA. The resulting mixture is reacted at 70-130°C for about 24 hr in an inert gas atmosphere, the reaction product is precipitated by the addition of water, and the precipitate is filtered and extracted with a solvent to separate a PVA-grafted terpolymer. This terpolymer is further heated to about 90-160°C for about 2-3 hr to form intermolecular ester bonds between the residual anhydride groups and the residual hydroxyl groups. Thus, a PVA-grafted terpolymer having excellent heat resistance and mechanical properties can be obtained.

COPYRIGHT: (C)1990,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to polyvinyl alcohol (PVA) terpolymers. Specifically, it relates to a polyvinyl alcohol grafted terpolymer grafted with an acrylate/maleic anhydride copolymer.

[Background of the invention]

Polyvinyl alcohol is a kind of waterproof polymer with excellent physical and mechanical properties, and is widely applied in adhesives, emulsions, textiles and anti-solvent coatings, but since it is a water-soluble polymer, polyvinyl alcohol Alcohol has poor waterproof properties.

In addition, polyvinyl alcohol, which has not yet been made into plastic, has very low thermoplasticity before being thermally decomposed.
There aren't many.

In order to overcome these disadvantages of polyvinyl alcohol,
The prior art involves the use of comonomers, grafting or co-reaction methods to modify polyvinyl alcohol.

The inventors first developed App1. Poly-, Sci.
, +30+3895 and 4045 (1985), “5 studies of Reaction”
s with Polys+ers, L The
Reaction of Melic Anhydr
ride with PVA and the
Properties of the Re5ulta
nt' and 5tudies of Reaction3w
ith Po1ya+ers, U, The R
action ofMeleic Anhydride
e with Acrylon″1trile ont
o PVA and the Properties o
f the Re5uttarit'', the present inventors have already discussed how to graft maleic anhydride (abbreviated as MA) and acrylonitrile to synthesize a polyvinyl alcohol grafted terpolymer and enhance its waterproof property. The initiator is potassium persulfate, and in that paper the inventors reported that the maleic anhydride in the side chain is rearranged to form a keto
They discovered that they form an olefin structure.

There are two general processes for making graft copolymers.

One is a method in which a monomer is polymerized at an activated position of a backbone, and the other is a method in which two different polymers are crosslinked through a polymerization reaction.

[Problem to be solved by the invention]

However, in the former method, maleic anhydride cannot be grafted onto polyvinyl alcohol, and the grafted side chain cannot have an acid anhydride group structure.

The present invention provides a polyvinyl alcohol graft terpolymer which has acid anhydride groups in its side chains and is substantially uniform and random.

[Means to solve the problem]

It contains 70-30% by weight of polyvinyl alcohol and 30-70% by weight of a homogeneous random acrylate/maleic anhydride copolymer of the following formula (1).

In the formula, R represents a hydrogen atom or a methyl group, preferably a methyl group, R゛ represents a C1-4 saturated alkyl group, m is 30-9
n represents the range of 0 mol%, n represents the range of 70-10 mol%, the method for producing the polyvinyl alcohol graft terpolymer includes the following steps, namely, acrylate monomer and maleic anhydride; Acid monomers are copolymerized to form an acrylate/maleic anhydride copolymer, and this copolymer is grafted onto polyvinyl alcohol to produce a polyvinyl alcohol graft terpolymer. Among them,
The graft polymerization is completed by a ring-opening esterification reaction of both the hydroxyl group contained in the polyvinyl alcohol and the acid anhydride group contained in the maleic anhydride.

The polyvinyl alcohol graft terpolymer of the present invention is further heat-treated to cause an intermolecular ester bond reaction between the remaining maleic anhydride hydroxyl groups and hydroxyl groups to form a crosslinked network structure.

The polyvinyl alcohol graft terpolymer of the present invention can also be used in the production of imide derivatives. Among them, the remaining acid anhydride groups contained in the terpolymer react with the amine,
First, a maleamic acid intermediate is produced, and then a maleimide derivative is produced through a dehydration treatment.

Polyvinyl alcohol is a crystalline polymer, whereas the acrylate/maleic anhydride copolymer to which it is grafted is an amorphous polymer. Therefore, after the polyvinyl alcohol graft terpolymer of the present invention is heat-treated, the remaining acid anhydride groups on the side chains and the hydroxyl groups on the main chain form intermolecular ester bonds, resulting in superior heat resistance and Produces mechanical properties.

R' in the acrylate/maleic anhydride copolymer of the chemical formula (1) in the polyvinyl alcohol graft terpolymer of the present invention is preferably a methyl group, particularly preferably a methacrylic acid ester, that is, R is CH3. , because it has excellent stability under the reaction conditions.

In a more preferred embodiment, m in formula (1) is 50-90
In mole %, n is within the range of 10-50 mole %.

The polyvinyl alcohol grafted terpolymer grafted in the above acrylate/maleic anhydride copolymer is
First, an acrylate monomer and a maleic anhydride monomer are copolymerized, and the resulting copolymer is graft-polymerized onto polyvinyl alcohol.

The acrylate monomer and maleic anhydride monomer are dissolved in a suitable solvent, such as dimethyl sulfoxide, and a free radical initiator is used that is soluble in the solvent. For example, when using an organic peroxide and azobisisobutyronitrile, the reaction temperature is preferably 40-80°C. In a preferred embodiment of the invention, the reaction product is precipitated with excess methyl alcohol and filtered. Among them, the maleic anhydride homopolymer and unreacted monomers were washed and separated with methyl alcohol, and the acrylate homopolymer was washed with toluene.
The desired polymer is obtained by separation.

The acrylate/maleic anhydride copolymer is dissolved in a suitable solvent such as dimethyl sulfoxide, and then polyvinyl alcohol is added to the solution.

The reaction mixture was heated to a temperature of 70-130°C for about 24 hours.
Keep time. The reaction is carried out with stirring in an inert atmosphere.
The reaction product is precipitated with water and filtered. The product collected by filtration contains a mixture of polyvinyl alcohol grafted terpolymer, unreacted polyvinyl alcohol, and unreacted acrylate/maleic anhydride copolymer, and the terpolymer is subjected to a series of solvent extractions as described below. Can be separated using technology.

The polyvinyl alcohol graft acrylate/maleic anhydride reaction product was determined by infrared spectrum analysis.
It was confirmed that it has the following general structure.

In the formula, A represents polyvinyl alcohol.

B represents an acrylate/maleic anhydride copolymer.

The bond between A and B is an acid anhydride group contained in the copolymer,
It is completed by a ring-opening esterification reaction of both hydroxy groups contained in the polyvinyl alcohol.

The polyvinyl alcohol graft acrylate/maleic anhydride ternary copolymer of the present invention is further heat-treated to form an intermolecular ester bond between both the residual acid anhydride group on the side chain and the residual hydroxyl group on the polyvinyl alcohol main chain. formation, resulting in better heat resistance and mechanical properties. For this purpose, the ester bond can be sufficiently and completely formed by carrying out the reaction at a temperature of about 90-160° C. for 2-3 hours.

The remaining acid anhydride groups on the side chains of the polyvinyl alcohol grafted acrylate/maleic anhydride terpolymer of the present invention include the terpolymer, ethylamine, n-aniline, n
-Butylamine, and amines such as n-octylamine react to form an n-substituted maleamic acid intermediate, which is purified under vacuum to form polyvinyl alcohol grafted acrylate)/n-maleimide. Produces a terpolymer. As is well known to those skilled in the art, imide groups on the side chains promote thermal stability of the terpolymer.

〔Example〕

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited.

Example 1 The polyvinyl alcohol was BF manufactured by Changchun Petrochemical Company.
17 products were adopted. Its DP is 1700, saponification degree is 98.5-99.2 mol%, and viscosity is 25-30C. Maleic anhydride (MA), methacrylic acid methyl ester (MMA), and dimethyl sulfoxide (D
MSO) is reagent grade purchased from Nippon Wako Pure Chemical Industries.

MMA is washed with an aqueous sodium hydroxide solution and distilled water, neutralized with hydrochloric acid, and then distilled and refluxed to remove calcium hydride and hydroquinone. Azobisisobutyronitrile (AIBN) initiator is reagent grade purchased from Nakarai Chemical Company, Japan. Other toluene, methyl alcohol, and acetone were used directly without being purified.

Copolymerization of MMA and MA (Reaction 1) The copolymerization reaction is carried out in a four-hole flask equipped with a stirrer, thermometer, condenser and nitrogen inlet. The general experimental process is as follows. 50 grams MMA and 48 grams MA
was dissolved in 20 °C of DMSO under stirring under nitrogen atmosphere, the reaction temperature was adjusted to 70 °C, 1 g of AIBN initiator was added, the reaction was continued for 5 h, and then the reaction product was quenched with excess methyl alcohol. Let it settle.

The reaction product precipitated with the above methyl alcohol is MMA.
-co-MA copolymer and unreacted MA, and MMA and MA
including mixtures of homopolymers, etc.

The mixture is separated by the following steps to purify the desired product.

After separation in the above steps, all substances are separated in vacuum for 3
Dry at a temperature of 0°C. The composition of the obtained MMA-co-MA is calculated using the following formula.

The calculated mol% values of MA and MMA in the MMA-co-MA copolymer are 0.53 mol% and 0.47 mol%, respectively.

Binding reaction of MMA-co-MA copolymer and PVA (reaction 2) 0M
After completely dissolving in SO120, 0 g of PVAl is added and the reaction is carried out at 100° C. for 24 hours and stirred in a nitrogen atmosphere. The reaction product is precipitated with water.

The precipitated product from reaction 2 above is PVA-g-MMA/
It is a mixture of MA graft terpolymer, unreacted pvA, and unreacted MMA-co-MA copolymer. These mixtures are separated and purified in the following steps.

Mixture of Reaction and Purification Products After separation in the above step, all substances were separated in vacuum for 3
Dry at a temperature of 0°C. The data of the above-mentioned graft terpolymer reaction can be calculated using the following formula.

Weight% of MA in the grafted terpolymer Weight% of MAA in the grafted terpolymer Weight% of PVA in the grafted terpolymer The main difficulties when synthesizing the above grafted terpolymer is formed by colloids. The reason for this is that the MMA-co-MA copolymer has many acid anhydride groups, and the PVA main chain also has many hydroxyl groups. Usually the ratio of PVA:MMA-co-MA is 2
It was discovered that this phenomenon is more likely to occur when the size is larger. The above-mentioned difficulties can be overcome by accurately adjusting the starting concentrations of the reactants.

The composition of PVA-g-MMA/MA synthesized by the above method for different weight % of PVA in the raw material is shown in Table 1 below.
As shown. Among them, M of MMA-co-MA raw material
The molar ratio of MAMMA is 0.47:0.53.

11 Composition of PVA-g-MMA/MA Preparation of membrane using grafted terpolymer A film is prepared using a 30% DMSO solution of the above terpolymer. Apply the solution to a clean glass slide,
After drying in a vacuum at a temperature of 30°C until the weight becomes constant, it is removed from the glass slide.

Heat treatment of the grafted terpolymer The above film is heated in vacuum at a temperature of 100° C. for 3 hours. The PVA-g-MMA/MA film undergoes an intermolecular ester bond reaction during the heating process to form a crosslinked network structure. The reaction is as follows.

Properties of graft terpolymer viscosity above PVA, MMA-co-MA and PVA-g-MM
The intrinsic viscosity of A/MA is 30 on the Ubbelohde viscometer.
Measured at °C and extrapolated the ηsr/C value to C-0.

Infrared Spectrum Infrared spectra were obtained using a JASCO model A-202 spectrophotometer on the film or mixture with KBr.

The water content film is first immersed in boiling water for 6 hours, then taken out, the film is dried on the surface with a filter paper, and then the weight is measured again. The moisture content of the film is calculated by the following subtraction:

The composition and yield are also entered in Table 2 below, and the obtained PVA-g-
The properties of the MMA/MA graft terpolymer are shown in FIGS. 1 to 6.

The tensile strength and breaking elongation of the mechanical film are ASTM D-6.
It was measured using a Tnstron type 1138 measuring machine according to the 38 measuring method.

Thermal analysis TGA measurements were performed on a DuPont 1090 B analyzer with a nitrogen atmosphere at a flow rate of 100/min and a heating rate of 20°C/min.

The properties of the above terpolymer are shown in FIGS. 1 to 6, respectively.

Example 2 The steps of Example 1 above are repeated except that the MMA and MA copolymer reaction is fed as shown in Table 2 below.

f of the obtained MMA/MA copolymer Supply monomer” ('El) Copolymer composition (mol) Intrinsic viscosity *a: ＾IBN (grams) −(HMA+MA
) (grams > xo, oiDMSO (grams)
-(HMA+MA) (grams) Xo, 2
*b: Example 1 As shown in FIG. 1, when the MA content in MMA-co-MA is increased, the [η] value clearly increases. This [η
] The increase in value can be interpreted as an increase in the number of side chains to be grafted due to higher MA content and higher reactivity with PVA. And when a higher content of MA is used, the [η] value of the PVA-g-MMA/MA graft terpolymer is originally (7)PVA (1,5d L/g)
This result also reflects that the graft terpolymer represented by the above structural formula (II) can contain one or more PVA main chains.

Figure 2 shows MMA-co-MA, PVA, PVA-g-
This is an infrared spectrum of the MMA/MA grafted terpolymer. The chain contains one carboxy group (17530).

All of the MA contained in the above PVA-g-MMA/MA does not exist in the form of acid anhydride, but some of the acid anhydride groups undergo an esterification reaction with PVA and are converted to ester groups. do. PVA! ! The molar ratio (M) of both the anhydride groups remaining in the chain and the starting anhydride groups in the MMA-co-MA feedstock can be determined by infrared spectroscopy.

In the PVA-g-MMA/MA graft terpolymer: AI''-aliXl +aIzXt +ai3X
3 +ar4X4At = a,,Xr
+ azlXg + az3Xs”
a! 4x4 among them, AI-1923-1770CI
Continuous absorbance of two carbonyl acid anhydride groups at 1, continuous absorbance of carbonyl acid anhydride groups at At =1770-1637 cm-', Xl5
Xo, X3, and X4 each represent the mole/L of succinic anhydride, succinic ester, methacrylic acid methyl ester, and acetate vinyl ester, and aij represents the absorption coefficient of band 1 of model number J.

The absorbance of PVA in this band can be omitted, since almost completely hydrolyzed PVA shows almost no carbonyl group absorption: a 14- a za-0 (3) The continuous absorbance of MMA in the A band is O. It is found that the molar ratio (F) of MA to MMA in the MMA-co-MA copolymer is expressed by the following formula.

(Xx +X,)/Xi F (5) The above value of M is obtained by merging <1) - (5).

M=Xr/(Xr+Xr)−(C)/(
C) + (D) (C) “am!, AI + ax
Ai F'-a12AttF(D)-ailAl F
-aHAI F measurement results are shown in Table 3 below.The 0M value decreases with increasing percentage of the weight of PVA supplied.

As shown in Figures 3 to 5, after heat treatment, the grafted terpolymer of the present invention has higher waterproofness and better mechanical properties than PVA, which is because the terpolymer has molecular This is because there is an ester bond between them.

As can be seen from the TGA thermogravimetric analysis diagram shown in FIG. 6, the graft terpolymer of the present invention is composed of PVA and MMA-co-
It has better heat resistance than MA and has a higher heat residual weight.

Example 3 PVA-g-MMA/NEM[D synthesis PVA-g-MM produced and purified in the above Example 1 test (2)
Dissolve 5 grams of A/MA in 50 ml of DMSO and make 1
Add 0 grams of N-aniline and bring the temperature of the solution to 100°C.
The reaction was carried out for 12 hours.

After the reaction, the reaction mixture was precipitated with a volume of methyl alcohol, and the precipitate was collected by filtration, further washed with methyl alcohol, and finally dried in vacuum to obtain PVA-g-
MMA/N Venge/1/? L/inic acid is obtained.

The PVA-g-MMA/N benzylmaleic acid was further added to D
A PVA-g-MMA/N benzyl maleic acid imide film is obtained by dissolving it in MSO, applying it in a film form in a vacuum, and heating the film in stages to reach 220° C. in 10 minutes in a vacuum.

[Brief explanation of the drawing]

Figure 1 shows that the mol% of MA contained in a methacrylic acid methyl ester/maleic anhydride copolymer (abbreviated as MMA-co-MA) is a polyvinyl alcohol grafted ternary copolymer grafted with the MMA-co-MA. Combined (PVA-g
- MMA/MA) on the intrinsic viscosity, in which the different curves indicate different weight percentages of polyvinyl alcohol in the respective feedstock. Figure 2 shows MMA-co-MASPVA and PVA-
The infrared spectrum of g-MMA/MA is shown. Figure 3 shows PVA-g-MMA/MA membranes with different weight percentages of polyvinyl alcohol in the raw material in dry and wet conditions.
shows the relationship between water content and water content. Figure 4 shows PVA-g-MMA/MA membranes with different weight percentages of polyvinyl alcohol in the raw material in dry and wet conditions.
The relationship between and tensile strength is shown. Figure 5 shows that the PVA-g-MMA/MA membrane has different weight percentages of polyvinyl alcohol in the raw material in dry and wet conditions.
The relationship between and the degree of fracture elongation is shown. Figure 6 shows PVA, MMA-co-MA, and PVA-
FIG. 2 shows a TGA thermal analysis diagram of g-MMA/MA.

Claims (1)

[Claims] 70-30% by weight of polyvinyl alcohol;
0% by weight of the following structural formula▲ Numerical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents a hydrogen atom methyl group, R' represents a C1-4 saturated alkyl group, m is 30-90 moles %, n represents a range of 70-10 mole %), the polymer comprises a substantially uniform random acrylate/maleic anhydride copolymer having a A modified polyvinyl alcohol graft terpolymer, characterized in that it is grafted onto the polyvinyl alcohol by a ring-opening esterification reaction of both hydroxyl groups and hydroxyl groups contained in the polyvinyl alcohol.