JPS6284104A - Rigid sheet - Google Patents

Abstract

PURPOSE:A rigid sheet, consisting of a molded article of a salt of a ternary or quaternary copolymer having a specific composition and further a material capable of drying in a short time in molding, having a high surface hardness and useful for applications, e.g. agricultural, packaging, building materials, etc. CONSTITUTION:A rigid sheet obtained by molding a salt of isobutylenemaleic acid or anhydride thereof-styrene copolymer, preferably sodium salt, potassium salt, ammonium salt, etc., or isobutylenemaleic acid or anhydride thereof-styrene- acrylic acid or derivative thereof [unit expressed by the formula (R1 and R2 are H, CH3 or C2H5)] copolymer. The number-average molecular weight of the above-mentioned copolymer is normally 5,000-200,000 and the salt thereof is produced by charging the respective components except isobutylene into a reaction vessel, cooling the charged components, deaerating the components, adding the isobutylene thereto, copolymerizing the components preferably at 45-150 deg.C for 1-10hr and neutralizing the resultant copolymer to form a salt thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hard sheet, and more particularly to a hard sheet made of a material with good moldability and having high surface hardness.

[Prior art and problems to be solved by the invention] Various types of plastic sheets are known for use in agriculture, packaging, building materials, insulation, etc. One of them is isobutylene. There are copolymers containing as a copolymerization component, for example, isobutylene-maleic anhydride copolymers.

That is, the salt of such a copolymer is molded into a sheet for practical use.

However, sheets formed from such copolymers have extremely low surface hardness, which limits their uses, and there is also the problem that it takes a long time to dry the sheets.

An object of the present invention is to solve these conventional problems and provide a hard sheet made of a material that dries in a short time during molding and has high surface hardness.

[Means for Solving the Problems] In order to achieve the above object, the present inventor has conducted extensive research focusing on the composition of the copolymer that is the material of the rigid sheet, and as a result, the inventors have solved the above-mentioned conventional two The present invention was completed after confirming that excellent effects can be obtained when a ternary or quaternary copolymer having a specific composition is used in place of the base polymer.

That is, the hard sheet of the present invention is made from a molded product of a salt of isobutylene-maleic acid or its anhydride-styrene copolymer or a salt of isobutylene-maleic acid or its anhydride-styrene-acrylic acid or its derivative copolymer. It is characterized by becoming.

[Specific Description] The hard sheet of the present invention is characterized by being composed of a salt of the above-mentioned ternary or quaternary copolymer, and the type of this salt is not particularly limited. Preferred examples include sodium salt, potassium salt, and ammonium salt.

In addition, acrylic acid or its derivative unit, which is one of the constituent components of the quaternary copolymer, has one formula: -C-CH2-
(However, R1 and R2 may be the same COOR2 or different, and each is a hydrogen atom,
(representing a methyl group or an ethyl group).

Such a copolymer of the present invention is produced, for example, as follows. That is, first, predetermined amounts of each copolymer component except isobutylene are charged into a reaction vessel, cooled and sufficiently degassed. Next, a predetermined amount of isobutylene is added and a copolymerization reaction is carried out with stirring. At this time, the reaction temperature is 30 to 200°C, preferably 45 to 150°C.
The reaction time is set to 0.5 to 20 hours, preferably 1 to 10 hours. In this copolymerization reaction, as necessary.

Solvents such as acetonitrile, nitromethane, nitroethane, methyl ethyl ketone, acetone, N,N-dimethylformamide, dimethyl sulfoxide, benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, dicumyl peroxide, azo Catalysts such as bisisobutyronitrile can be used.

Thereafter, the copolymer thus obtained is neutralized with an alkali to produce a copolymer salt. At this time, the alkali used is preferably sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, ammonia, sodium acetate, urea, thiourea, organic amines, etc. The reaction temperature of this neutralization reaction is 20 ~
It is preferable to set the temperature to 150°C and the reaction time to 0.5 to 10 hours.

Note that this copolymer usually has a number average molecular weight of 3
．． 000 to 400,000, preferably 5.0
00 to 200.000.

The hard sheet of the present invention is obtained by molding the above-mentioned copolymer, but at this time, in addition to the copolymer,
If necessary, titanium oxide, calcium carbonate, barium sulfate, zinc oxide, f! Inorganic fillers such as magnesium aluminide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, talc, clay; polyvinyl alcohol, carboxymethyl cellulose, hydroxymethyl cellulose 5 and droxyethyl cellulose, starch, glue, sodium polyacrylate Water-soluble resins such as nidioctyl phthalate, dibutyl phthalate, di(2-ethylhexyl) adipate, tricresyl phosphate, and other plasticizers may be contained.

In addition, as a molding method, ordinary molding methods can be applied, such as injection molding, extrusion molding, compression molding, etc., but cast molding is the most suitable method. It has the advantage that it can be easily formed into a sheet by such a simple molding method.

[Example] Examples 1 to 6 Internal volume 19. Into an autoclave, charge the indicated amounts of the indicated ingredients except inbutylene, and cool to -10°C.

At the same time, the inside of the container was sufficiently degassed. Then, inbutylene was added in the indicated amount and acetonitrile 46 was added as a solvent.
0cc, add 0.8g of benzoyl peroxide as a catalyst,
A copolymerization reaction was carried out at 110° C. for 2 hours while stirring at 400 rpm, and then the product was poured into water to obtain a copolymer. Number average molecular weight, acid value (mgKOH/g), amount of inbutylene (wt%), amount of maleic anhydride (wt%), amount of styrene (wt%), and amount of methyl acrylate (wt%) of the obtained copolymer ) are shown in the table.

Thereafter, an amount of sodium hydroxide aqueous solution was added to the copolymer in an amount that would give a neutralization degree of 1 to bring the concentration to 20% by weight.
A neutralization reaction was carried out at 90°C for 6 hours to produce a copolymer salt, which was poured into a 100ml polypropylene disc cup and left at room temperature to form a 5μl thick disc. A shaped sheet was produced. The surface hardness (Shore D) of the obtained sheet was determined according to ASTM D l48.
4-597, and the results are shown in the table. In addition, the above copolymer was separately injected onto a glass plate to a thickness of one layer, and the drying time was determined according to JIS K 540.
0, and the results are also listed in the table.

Comparative Example 1 A sheet was produced in the same manner as in Examples 1 to 6 above, except that only the two indicated components were used as copolymerization components,
A similar evaluation test was conducted and the results are shown in the table.

Comparative Example 2 In the copolymerization reaction, m-n-butyl vinegar was used as a solvent,
Except that azobisisobutyronitrile was used as a catalyst and the reaction temperature was 55°C and the reaction time was 6 hours.
A sheet was manufactured in the same manner as in Comparative Example 1 above, and evaluation tests were conducted in the same manner, and the results are shown in the table.

[Effects of the Invention] As is clear from the above explanation, the hard sheet of the present invention is made of a copolymer with a novel composition that dries in a short time during molding, and has extremely high surface hardness. Therefore, it has great industrial value in various fields of use, such as for mustard vegetables, packaging, building materials, and insulation sheets.

Claims (1)

[Scope of Claims] 1. Consists of a salt of isobutylene-maleic acid or its anhydride-styrene copolymer or a molded product of a salt of isobutylene-maleic acid or its anhydride-styrene-acrylic acid or its derivative copolymer A hard sheet characterized by: 2. The hard sheet according to claim 1, wherein the copolymer has a styrene content of 10% by weight or more.