JPH03203932A - Melt molding of water-soluble vinyl alcoholic polymer - Google Patents

Abstract

PURPOSE:To industrially advantageously obtain the subject polymer having solubility in water, softness, fragrance-keeping property and resistance to oil, etc., by subjecting a specific oxyalkylene group-containing vinyl alcohol copolymer to melt molding in an anhydrous condition. CONSTITUTION:An oxyalkylene group-containing vinyl alcohol copolymer used as a raw material contains (A) a mol% vinyl alcohol unit expressed by formula I, (B) b mol% vinyl ester unit expressed by formula II (R<1> is alkyl) and (C) c mol% oxyalkylene allyl ether unit expressed by formula III [R<2> and R<3> are H or alkyl; R<4> is H, alkyl or (substituted) phenyl; n is 1-300] satisfying 0.1<=c<=20, 50<=100a/(a+b)<=100 and >=5g/10min melt index (210 deg.C, 2160g load). Then, said raw material is subjected to melt molding in substantially anhydrous condition to afford the aimed polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application in Coastal Industry The present invention is directed to the melting of water-soluble vinyl alcohol copolymers containing vinyl alcohol units (A), vinyl ester units (B) and oxyalkylene allyl ether units (C). It relates to a method of molding.

Conventional technology Polyvinyl alcohol molded products, such as films,
It has excellent properties such as fragrance retention, transparency, oil resistance, antistatic properties, oxygen barrier properties, and heat retention, and it also has hydrophilicity and water solubility or water dispersibility, so it is better than ordinary hydrophobic polymers. It can also be used in applications that are not suitable for films.

As a method for obtaining a film from polyvinyl alcohol, a method is usually employed in which the polymer is dissolved in water and cast. In this case, the obtained film is flexible under high temperature conditions, but loses its flexibility under low humidity conditions. Therefore, in order to maintain flexibility even under low humidity conditions, plasticizer such as glycerin is added during casting. The agent is blended.

As a method of obtaining films and other molded products from polyvinyl alcohol, a method of melt-extruding the polymer in a water-containing state is also known. In this case as well, a plasticizer is used in combination in order to maintain the flexibility of the resulting molded product.

Attempts have also been made to melt extrude polyvinyl alcohol under substantially anhydrous conditions, but since polyvinyl alcohol has a high softening point and its softening point is close to the thermal decomposition temperature, melt extrusion of polyvinyl alcohol alone has been difficult. Have difficulty. Therefore, when polyvinyl alcohol is melt-molded, a large amount of a plasticizer such as glycerin is blended and the mixture is subjected to extrusion molding.

Note that injection molding of polyvinyl alcohol is generally not carried out.

Polyvinyl alcohol is produced by polymerizing vinyl acetate and then saponifying it, but by using a comonomer together during polymerization, it is possible to obtain copolymerized modified polyvinyl alcohol. By reacting with other compounds, polyvinyl alcohol can be made to have post-fixed properties.These modified polyvinyl alcohols have the above-mentioned properties of polyvinyl alcohol, but are Properties based on modified groups are added.

As one of such modified polyvinyl alcohols, vinyl alcohol polymers into which oxyalkylene units are introduced are known, and various domestic and foreign applications have been filed, for example, as follows.

For example, US Pat. No. 1,971,662, US Pat.
In specification No. 44570 and specification No. 2990398,
An oxyethylene group-containing polyvinyl alcohol obtained by addition-reacting ethylene oxide to polyvinyl alcohol is shown.

US Pat. No. 3,033,841, US Pat. No. 4,369,281
The specification discloses an oxyalkylene group-containing polyvinyl alcohol obtained by saponifying a polymer obtained by graft polymerizing vinyl acetate in the coexistence of polyalkylene glycol.

U.S. Patent No. 4618648, U.S. Patent No. 467536
Specification No. 0 discloses a copolymer of vinyl alcohol and poly(alkyleneoxy)acrylate, and this copolymer can be injection molded or extruded, and the molded product obtained is water-soluble. It has also been shown to be flexible.

JP-A-59-1655408 discloses a modified polyvinyl alcohol obtained by saponifying a copolymer of an unsaturated monomer containing an oxyalkylene group and vinyl acetate. The publication lists a wide variety of uses, including molded products as an example of the use, but does not disclose the molding method.

JP-A-1-158016 discloses a water-resistant flexible film made of an oxyalkylene group-containing vinyl alcohol polymer film.

The publication states, ``For film formation, methods such as casting an aqueous solution of the polymer, heating extrusion under hydrous conditions, melt extrusion, etc. are adopted,'' but all examples are It involves a casting method, and regarding the melt extrusion method (
Regarding the method of heat extrusion under hydrous conditions), there is only this statement.

Problem to be Solved by the Invention The method for molding polyvinyl alcohol by a casting method is as follows:
It is necessary to adjust the aqueous solution, the film forming speed is slow,
There are various disadvantages compared to the melt extrusion method, such as the long time required for drying after film formation. Similar disadvantages arise when a plasticizer is used in combination to impart flexibility to the molded article, and the problem of bleeding caused by the added plasticizer also arises.

The method of melt-extruding polyvinyl alcohol in a water-containing state also has the disadvantage that it takes a long time to dry after molding.

When a plasticizer is used in combination to impart flexibility to the molded product, there are disadvantages similar to those described above, as well as a new problem of bleeding caused by the softener added.

The method of blending a large amount of plasticizer with polyvinyl alcohol and melt-extruding it may cause the blended plasticizer to bleed onto the surface of the molded product, causing stickiness or poor adhesion when laminated with other base materials. There is.

In this regard, the vinyl alcohol polymer into which oxyalkylene units have been introduced has the advantage that it can omit the addition of a plasticizer, since it itself has flexibility.

However, the oxyethylene group-containing polyvinyl alcohols described in U.S. Pat. No. 1,971,662, U.S. Pat. No. 2,844,570, and U.S. Pat. , since it involves secondary processing, there is a disadvantage in that productivity is poor.

US Pat. No. 3,033,841, US Pat. No. 4,369,281
The oxyalkylene group-containing polyvinyl alcohol described in the specification has low reactivity during graft polymerization to alkylene glycol during its production, and cannot be said to be practical.

U.S. Patent No. 4618648, U.S. Patent No. 467536
The vinyl alcohol/poly(alkyleneoxy)acrylate copolymer described in specification No. 0 is obtained by copolymerizing vinyl acetate and poly(alkyleneoxy)acrylate, and then
Although it is produced by saponification, the oxyalkylene group is likely to be eliminated during the saponification reaction, so the product after saponification is actually a mixture with the eliminated alkylene glycol or polyalkylene gelicol.

JP-A-59-1855408 only discloses the production and expected uses of oxyalkylene group-containing vinyl alcohol polymers, but does not disclose anything about melt molding or other molding methods. .

Although JP-A-1-158016 suggests melt molding of an oxyalkylene group-containing vinyl alcohol polymer, when melt molding is actually attempted, smooth melt molding is not easy.

It is against this background that the present invention was made for the purpose of providing an industrially applicable method for melt-molding an oxyalkylene group-containing vinyl alcohol copolymer under substantially anhydrous conditions. be.

Means for Solving the Problems The present invention provides a method for melt molding a water-soluble vinyl alcohol polymer.

The vinyl alcohol unit (A), vinyl ester unit (B) and oxyalkylene allyl ether unit (C) represented by the following formula % () () () are respectively a mol %, b mol % and 0 mol %. R1 in (B) is an alkyl group, R2 in (C)
and R3 is H or an alkyl group, R4 in (C)
is H, an alkyl group, a phenyl group, or a substituted phenyl group, and n is 1 to 300, and satisfies the following relationships: 0.1≦C≦20 and 50≦100a/(a+b)≦100, and This method is characterized in that an oxyalkylene group-containing vinyl alcohol copolymer having a melt index of 5 g/10 sin or more at a temperature of 210° C. and a load of 2180 g is melt-molded under substantially anhydrous conditions.

The present invention will be explained in detail below.

The oxyalkylene group-containing vinyl alcohol copolymer used in the present invention contains vinyl alcohol units (A), vinyl ester units (B), and oxyalkylene allyl ether units (C) in a mol%, b mol%, and 0 mol%, respectively.
Here, R1 in (B) is an alkyl group (especially a methyl group), R2 and R3 in (C) are H or an alkyl group (especially both R2 and R3 are H, or one of them is H and the other is a methyl group),
R4 in (C) is H, an alkyl group, a phenyl group or a substituted phenyl group, and n is 1 to 300 (especially 3 to 50)
A typical example of the vinyl ester unit (B) is vinyl acetate, and the oxyalkylene allyl ether unit (C)
A typical example is polyoxyethylene allyl ether.

These are polyoxyethylene methalyl ether, polyoxypropylene allyl ether, and polyoxypropylene methalylether.

The above copolymer first has the following relationship O0l≦C≦20. 50≦100a/(a+b)≦100 is required to satisfy.

The first formula indicates that the proportion of oxyalkylene allyl ether units (C) in the copolymer is 0.1 to 20 mol%, and the proportion of this unit (C) is 0.1 mol%.
If it is less than 20 mol %, the modifying effect will be insufficient, and if it exceeds 20 mol %, the original properties of the vinyl alcohol copolymer will be impaired. A particularly preferred range is 0.1 to 5 mol%.

The second formula means that the degree of saponification of the vinyl ester component before saponification is 50 to 100 mol%.

If the degree of saponification is less than 50 mol%, the properties of the vinyl alcohol group such as hydrophilicity, fragrance retention, oil resistance, antistatic properties, oxygen barrier properties, and heat retention properties cannot be sufficiently obtained, which is a preferable range for #. is 80 to 100 mol%.

Note that, if necessary, it may contain up to about 30 mol% of heptamer units other than (A), (B), and (C), and such units include, for example, α-olefins (ethylene, (furopylene, long-chain α-olefin, etc.), ethylenically unsaturated carboxylic acid monomers (acrylate, methacrylate, acrylonitrile, methacrylate trile, vinyl chloride, vinyl ether, etc.).

In the above copolymer, it is useful to use vinyl acetate as the unit (B). Moreover, in this case, if the proportion of the oxyalkylene unit -+(:)IR2-CHR3-0 in the unit (C) in the entire resin is 3 to 40% by weight, -
The effect becomes more and more noticeable. That is, focusing on the oxyalkylene units, not only is the molar proportion of (C) in the copolymer 0.1 to 20 mol% (preferably 0.1 to 5 mol%), but also the oxyalkylene units in (C) are The weight proportion of alkylene units is 3 to 40% by weight (preferably 5% by weight of the entire resin).
~40% by weight). This indicates that in order to perform smooth melt molding under anhydrous conditions, there are restrictions on the degree of localization/delocalization of the oxyalkylene units in the copolymer and the length of the oxyalkylene units. Also, the number of n is 3 to 50, and the degree of saponification is 80 to 10.
0 mol% is a highly practical range.

Furthermore, the oxyalkylene group-containing vinyl alcohol copolymer used in the present invention can be used at a temperature of 210°C and a load of 2180 g.
It is required that the melt index is 5 g/10 inch or more. If this value is less than 5 g/10 sin, it is difficult to perform smooth melt molding even if other conditions are met. [
■Measured by φ×10■.

In this way, in the present invention, melt molding under substantially anhydrous conditions becomes industrially possible only when an oxyalkylene group-containing vinyl alcohol copolymer that satisfies each of the above conditions is used. .

The above-mentioned oxyalkylene group-containing vinyl alcohol copolymer is obtained by polymerizing the heptamers constituting the vinyl ester unit (B) and the oxyalkylene allyl ether unit (C) together with other copolymerizable heptamers as necessary. , and then saponification. Most or all of the vinyl ester units (B) are converted into vinyl alcohol units by saponification.

As the polymerization method, a solution polymerization method is usually adopted, and depending on the case, a suspension polymerization method, an emulsion polymerization method, etc. can also be adopted.

As the saponification reaction, an alkali saponification method, an acid saponification method, etc. are employed.

Melt molding of the oxyalkylene group-containing vinyl alcohol copolymer is performed under substantially anhydrous conditions. Substantially anhydrous means that the water content is desirably 1% by weight or less, particularly 0.5% by weight or less, although there is no problem even if about 5% by weight or less of water remains.

Plasticizers such as polyhydric alcohols can be added during melt molding, but flexibility can be obtained without the use of plasticizers, and the use of plasticizers may worsen the properties of the molded product. , it is better not to use it.

During melt molding, various additives such as fillers, colorants, and stabilizers can be blended.Other polymers can also be blended within the scope of the invention, or vice versa. The above oxyalkylene group-containing vinyl alcohol copolymer can also be blended with other polymers.

As the melt molding method, any melt molding method can be employed, including injection molding, extrusion molding, and transfer molding.

The most important melt molding method is the injection molding method.
It should be said that it is unique that water-soluble vinyl alcohol-based polymers can be injection molded in an anhydrous or unplasticized state. Incidentally, U.S. Pat. No. 4,618,648 and U.S. Pat. No. 4,675,360 disclose injection molding or extrusion molding of a copolymer of vinyl alcohol and poly(alkyleneoxy)acrylate, but the saponification reaction Since the alkylene glycol or polyalkylene gelol produced by elimination acts as a plasticizer, it is actually injection molded with a plasticizer in it.

Injection conditions include cylinder temperature of 150 to 250°C;
Mold temperature 30~100℃, injection pressure SOO~2000k
The conditions for g1C shoes 2 are preferably adopted. Although the oxyalkylene group-containing vinyl alcohol copolymer specified above can be injection molded, it is difficult to mold compared to other general-purpose molding resins, so strict conditions must be set. .

Among melt molding, extrusion molding is also important. For extrusion molding,
It also includes blow molding, inflation molding, coextrusion molding, and extrusion coating.

During extrusion molding, set the temperature at 150 to 300°C, and set the temperature at the screw compression section to be lower than the temperature at the discharge section.
Extrusion molding, which is preferably carried out at a temperature 0°C higher, requires strict conditions.

Actions and Effects of the Invention The copolymer obtained by copolymerizing the monomers constituting the vinyl ester unit (B) and the oxyalkylene allyl ether unit (C) will not react even if the copolymer is subjected to a saponification reaction. The oxyalkylene group of the oxyalkylene allyl ether unit (C) never leaves.

In the oxyalkylene group-containing vinyl alcohol copolymer of the present invention, vinyl alcohol units (A) and oxyalkylene allyl ether units (C) are distributed in an appropriate ratio, and the oxyalkylene units in the units (C) are Since the weight proportion is set within a specific range, the degree of localization/delocalization of the oxyalkylene units and the length of the oxyalkylene units are balanced so as to be suitable for melt molding. In addition, the melt index of the entire copolymer is also specified to be suitable for melt molding.

Therefore, if specific molding conditions are selected, even in melt molding such as injection molding, smooth melt molding that can be employed industrially becomes possible even in substantially anhydrous conditions (and without the use of plasticizers).

The obtained molded product is not only water-soluble and flexible, but also has properties based on the vinyl alcohol unit (A) such as fragrance retention, oil resistance, antistatic property, oxygen barrier property, and heat retention property. There is.

Note that the molded product can also be made waterproof by adding a crosslinking agent during molding or by subjecting the obtained molded product to heat treatment or crosslinking agent treatment.

Example Next, the present invention will be further explained with reference to Examples.

<Production of copolymer> Example 1 Polyoxyethylene monoallyl ether having an average number of added moles of oxyethylene of 25 and vinyl acetate were copolymerized in methanol in the presence of azobisisobutyronitrile,
After expelling the remaining monomers, a methanol solution of sodium hydroxide was added to saponify the mixture. The copolymer was filtered out from the slurry produced by the saponification reaction, washed and dried to obtain the desired oxyalkylene group-containing vinyl alcohol copolymer.

Vinyl alcohol unit (A) (7) IG of this copolymer
Ia was 83 mol%, the proportion of vinyl acetate units (B) was 8 mol%, and the proportion C of oxyethylene allyl ether units (C) was 1 mol%.

From this, it can be seen that a + b + C = 100 mol% c = 1 mol% 100a/(a+b) = 94.

Further, it can be seen that the weight ratio of oxyethylene units to the total weight of (A), (B) and (C) is 19% by weight.

The melt index of this copolymer at a temperature of 210° C. and a load of 2180 g was 15 g/10 m1n.

The viscosity of a 4% by weight aqueous solution of this copolymer is 3
．． It was 8 cps/20°C.

The characteristic values of the E2 copolymer are shown in Table 1 below.

Examples 2 to 6 According to Example 1, copolymers having various characteristic values as shown in Table 1 were produced.

Comparative Examples 1 to 4 According to Example 1, three copolymers having various characteristic values as shown in Table 2 were produced. The copolymers of these comparative examples are:
It does not completely have the characteristic values specified in the present application.

<Molding material> The oxyalkylene group-containing vinyl alcohol copolymers of Examples 1 to 6 and Comparative Examples 1 to 4 were dried to a water content of 0.1% by weight or less, and then fed to an extruder to form a linear shape. After extrusion, it was cut into pellets. This pellet was used for melt molding as described below.

<injection molding> The following injection molding conditions were adopted.

Injection molding machine Japan Steel Works N100 type automatic injection molding machine 200℃ 210℃ 50℃ 700 kg/cm2 Kuru 20 seconds Screw cross line temperature Discharge section temperature Mold temperature Injection pressure molding Cytoextrusion Adopted.

Extruder Twin screw extruder screw, -L 1150mm, 040mmφL
/D = 28.75 Rotation speed 5 Orpm Cylinder temperature Compression section 200°C T-die temperature 180°C <Results> The results of injection molding and extrusion molding and the properties of the molded product obtained by these moldings are shown in m below. 43ゑh-
Injection/extrusion moldability, water solubility, flexibility, blocking, and bleeding were determined as follows.

Injection moldability and extrusion moldability were determined by the presence or absence of rough skin on the surface of the molded product, and the case where there was no rough skin etc. was set as 0.

Water solubility is measured by placing a test piece (
Soak 10 Chinese intestines x 5 (1++ m x 1 l) for 10
The solubility level after minutes was observed and judged in the following three stages. In addition, the presence or absence of turbidity of the water after the test was observed.

O: Dissolved residue is less than 30% by weight Δ: Dissolved residue is 30% by weight or more and less than 70% by weight ×:
Dissolved residue is 70% or more Flexibility is according to JIS K 7203, 20℃, 80℃
SR)I The condition of the test piece that had been conditioned for 30 days was observed, and if it was flexible, it was judged as O. Furthermore, the flexural modulus was measured.

Blocking was performed using a test piece (10■■X 5Gs Peng Xis
■) stacked, under a load of 5g/cm2, 20℃, 72℃
The state after being left in $RH for 18 hours was observed, and the case where the two test pieces were not attached at all was rated 0, the case where they were slightly attached was rated Δ, and the case where they were attached was graded x.

Bleeding is carried out at 20℃, 85$RH11.
8 hours) Toku 40℃, 80! RH, 8 o'clock fil> ,!
-(7) Il conditions were alternately brought 30 times each time, and the condition of the surface of the molded product was observed, and the case where there was no bleeding was judged as 0.

From the above results, the copolymers of Examples have excellent injection moldability and extrusion moldability, and the molded products have excellent water solubility and flexibility, as well as blocking and extrusion moldability.
It can be seen that no bleeding occurs.

(Melt moldability of polyvinyl alcohol) For reference, melt molding of polyvinyl alcohol was also attempted.

The following polyvinyl alcohol was used for melt molding.

■ is the degree of polymerization, ■ is the degree of saponification (mol%), ■ is the viscosity of an aqueous solution with a concentration of 4% by weight (Cps/20°C), and ■ is the temperature of 210
The melt index at °C and a load of 2180 g, ■ is the amount (parts by weight) of the plasticizer (glycerin) based on 100 parts by weight of polyvinyl alcohol.

■ PVA-1200 PVA-2300 PVA-3300 PVA-4200 ■ ■ ■ 93 3.2 24 88 3.3 28 80 :14 34 93 3.2 28 Above PVA-1, PVA-2, PVA-3, PVA −
The results obtained when extrusion molding was carried out under the same extrusion molding conditions as in Example 1 are shown below.

PVA-I PVA-2 PVA-3 PVA-4 O good 0 good ΔCloud point present ×Cloudy No X No x No x 0 present No 0 Δ Slightly present × Yes No O No 0 No O No 0 ×Yes

Claims (1)

[Claims] 1. The following formulas ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (A) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (B) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (C) Contains a mol%, b mol%, and c mol% of vinyl alcohol units (A), vinyl ester units (B), and oxyalkylene allyl ether units (C) represented by the following, respectively, and R^1 in (B) is an alkyl group. , R in (C)
^2 and R^3 are H or an alkyl group, R^4 in (C) is H, an alkyl group, a phenyl group or a substituted phenyl group, n is 1 to 300, and the following relationship 0.1≦c≦ 20, 50≦100a/(a+b)≦100, and has a melt index of 5 g/10 min or more at a temperature of 210° C. and a load of 2160 g. A method for melt-molding a water-soluble vinyl alcohol polymer, the method comprising melt-molding under anhydrous conditions. 2. (B) is a vinyl acetate unit, and (C) is an oxyalkylene unit ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
2. The melt molding method according to claim 1, wherein the proportion of the total resin is 3 to 40% by weight. 3. All of the following relationships 3≦n≦50, 0.1≦c≦5, 80≦100a/(a+b)≦100 are satisfied, and among (C), oxyalkylene unit▲mathematical formula, chemical formula, table, etc. The melt molding method according to claim 1, wherein the proportion of ▼ in the entire resin is 5 to 30% by weight. 4. The melt molding method according to claim 1, wherein the melt molding is performed substantially without using a plasticizer. 5. Melt molding is injection molding, and the injection molding is performed at a cylinder temperature of 150 to 250°C, a mold temperature of 30 to 100°C,
5. The melt molding method according to claim 1, wherein the melt molding method is carried out under conditions of an injection pressure of 500 to 2000 kg/cm^2. 6. The melt molding is extrusion molding, and the extrusion molding is carried out by setting the die temperature to 150 to 300 °C and setting the screw compression part temperature to 5 to 30 °C higher than the discharge part temperature. The melt molding method according to any one of claims 1 to 4.