JP5824479B2 - Modified polyvinyl acetate and adhesive - Google Patents

Description

The present invention relates to a modified polyvinyl acetate and an adhesive using the same. More specifically, the present invention relates to a modified polyvinyl acetate having improved alkali resistance and an adhesive having excellent adhesive strength using the same.

Polyvinyl acetate is widely used as a raw material for paints, pressure-sensitive adhesives, adhesives and coating agents, denture stabilizers, chewing gum bases, FRP anti-shrinkage agents, vibration damping materials and the like.

As an adhesive or coating agent using polyvinyl acetate, an aqueous silicon dioxide dispersion having a specific average particle diameter is added to polyvinyl acetate (see Patent Document 1), or an epoxy group containing polyvinyl acetate. A compound (see Patent Document 2) containing a compound, an acidic compound, a non-asbestos filler, and a surfactant is known.

  Adhesives and coating materials using polyvinyl acetate can be used without problems in normal use. However, since polyvinyl acetate has a low alkali resistance, there are cases where the coating is damaged or deteriorated when used in a place exposed to an alkaline environment. Moreover, when using an adhesive or a coated material for a long time at high temperature, the adhesive layer or the coating film may deteriorate and peel off. For this reason, the polyvinyl acetate which improved alkali resistance and the adhesive agent excellent in the adhesive strength using this were calculated | required.

JP 2007-314786 A JP 2001-207153 A

The present invention provides polyvinyl acetate with improved alkali resistance and an adhesive having excellent adhesive strength using the polyvinyl acetate.

The above-mentioned problem can be solved by including a structural unit derived from a specific compound in a binding unit constituting polyvinyl acetate.

That is, the present invention relates to a bond unit derived from a vinyl acetate-derived bond unit of 45 mol% or more and 99.99 mol% or less, a fatty acid vinyl ester-derived bond unit of 1 mol% or more and 50 mol% or less, and a monomer having a carboxyl group. It is a modified polyvinyl acetate having 0.01 mol% or more and 5 mol% or less.
The fatty acid vinyl ester copolymerized with vinyl acetate is preferably at least one selected from fatty acid vinyl esters having 20 or less carbon atoms, in particular, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, It is preferably at least one selected from vinyl palmitate, vinyl stearate, vinyl cinnamate, and vinyl neodecanoate.
The monomer having a carboxyl group to be copolymerized with vinyl acetate is at least one selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid monoester, fumaric acid monoester, and itaconic acid monoester. It is preferable that
The average degree of polymerization of the modified polyvinyl acetate is preferably 1000 or more and 8000 or less.
The modified polyvinyl acetate can be made into an adhesive by mixing an organic solvent and an inorganic filler.

ADVANTAGE OF THE INVENTION According to this invention, the adhesive agent excellent in the adhesive strength using the polyvinyl acetate which improved alkali resistance and this can be obtained.

The modified polyvinyl acetate of the present invention comprises (1) 45 mol% or more and 99.99 mol% or less of a bond unit derived from vinyl acetate, and (2) 1 mol% or more and 50 mol% or less of a bond unit derived from a fatty acid vinyl ester, (3) A modified polyvinyl acetate having a linkage unit derived from a monomer having a carboxyl group of 0.01 mol% or more and 5 mol% or less.
Since the modified polyvinyl acetate has a bond unit derived from a fatty acid vinyl ester in its molecule, it has excellent alkali resistance. Moreover, since it has the bond unit derived from the monomer which has a carboxyl group in a molecule | numerator, when it is set as an adhesive agent, it has the effect of improving the adhesive strength.

(1) Vinyl acetate Vinyl acetate forms the skeleton of the resulting modified polyvinyl acetate. The amount of vinyl acetate-derived bond units (copolymerization amount) in the modified polyvinyl acetate is in the range of 45 mol% or more and 99.99 mol% or less. If the copolymerization amount is less than 45 mol%, the adhesive strength is lowered when the resulting modified polyvinyl acetate is used as an adhesive. On the other hand, when the copolymerization amount exceeds 99.99 mol%, the alkali resistance of the resulting modified polyvinyl acetate is lowered. The lower limit value of the copolymerization amount of vinyl acetate is preferably 70 mol%, more preferably 75 mol%. The upper limit of the copolymerization amount of vinyl acetate is desirably 95 mol%, more preferably 90 mol%.

(2) Fatty acid vinyl ester The fatty acid vinyl ester is copolymerized in the modified polyvinyl acetate in order to improve the alkali resistance of the resulting modified polyvinyl acetate. The copolymerization amount of the fatty acid vinyl ester is in the range of 1 mol% to 50 mol%. If the copolymerization amount is less than 1 mol%, the effect of improving the alkali resistance of the resulting modified polyvinyl acetate cannot be obtained. Moreover, when the copolymerization amount of fatty acid vinyl ester exceeds 50 mol%, when the modified polyvinyl acetate obtained is used as an adhesive, the adhesive strength decreases.
The lower limit of the copolymerization amount of the fatty acid vinyl ester is preferably 5 mol%, more preferably 10 mol%. The upper limit of the copolymerization amount of the fatty acid vinyl ester is preferably 25 mol%, more preferably 30 mol%.

The fatty acid vinyl ester is preferably a fatty acid vinyl ester having 5 to 20 carbon atoms. When a fatty acid ester having less than 5 carbon atoms is used, the alkali resistance of the resulting modified polyvinyl acetate may not be improved. Moreover, the water resistance may also decrease.
When the fatty acid ester having more than 20 carbon atoms is used, the alkali resistance of the resulting modified polyvinyl acetate may be inferior.
The lower limit of the carbon number of the fatty acid vinyl ester used in the present invention is preferably 8 and more preferably 12, and the upper limit of the carbon number is preferably 14 and more preferably 16, the alkali resistance of the resulting modified polyvinyl acetate. In addition, it is desirable because the adhesive strength is improved.

The compound having a fatty acid vinyl ester unit having 5 to 20 carbon atoms is not particularly limited, but vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, cinnamic acid. Vinyl, vinyl neodecanoate, etc.

(3) Monomer having a carboxyl group The monomer having a carboxyl group is copolymerized in order to improve the adhesive strength when the resulting modified polyvinyl acetate is used as an adhesive. The copolymerization amount of the monomer having a carboxyl group is in the range of 0.01 mol% to 5 mol%. If the copolymerization amount is less than 0.01 mol%, the effect of improving the adhesive strength of the obtained adhesive cannot be obtained. On the other hand, if the copolymerization amount of the monomer having a carboxyl group exceeds 5 mol%, the resulting modified polyvinyl acetate becomes difficult to dissolve in an organic solvent, and the adhesive cannot be produced.
The lower limit of the copolymerization amount of the monomer having a carboxyl group is preferably 0.10 mol%, more preferably 0.15 mol%. The upper limit of the copolymerization amount of the monomer having a carboxyl group is preferably 4 mol%, more preferably 3 mol%.

The monomer having a carboxyl group is not particularly limited, but monomers such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, monomethyl maleate, monoethyl maleate, monobutyl maleate, maleate Monopropyl acid, monopentyl maleate, monohexyl maleate, monoheptyl maleate, monooctyl maleate, monoester maleate, monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monopropyl fumarate, monopentyl fumarate, Fumarate monoesters such as monohexyl fumarate, monoheptyl fumarate, monooctyl fumarate, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monopropyl itaconate, itaconate mono Pentyl, monohexyl itaconate, Monohepuchiru itaconic acid, itaconic acid monoesters and itaconic acid mono octyl.

In order to obtain the modified polyvinyl acetate of the present invention, for example, in the presence of the modified polyvinyl alcohol described in WO 2006/095462 pamphlet, the above-mentioned vinyl acetate, fatty acid vinyl ester, and a monomer having a carboxyl group are used. May be copolymerized by suspension polymerization.

The concentration of the modified polyvinyl alcohol in the polymerization liquid for suspension polymerization is adjusted to a concentration of 0.05 to 0.5%. When the concentration of the modified polyvinyl alcohol is adjusted to this range, the viscosity of the polymerization solution at the time of suspension polymerization becomes appropriate and the polymerization reaction is efficiently performed while maintaining the protective colloid properties.

The average degree of polymerization of the modified polyvinyl acetate is preferably adjusted to a range of 1000 or more and 8000 or less. By adjusting the average degree of polymerization of the modified polyvinyl acetate within this range, when the modified polyvinyl acetate is used as an adhesive, the solution viscosity becomes appropriate and the coating workability can be improved.

The average degree of polymerization of the modified polyvinyl acetate is arbitrarily adjusted by appropriately adjusting the polymerization temperature and polymerization time, the concentration in the polymerization solution during suspension polymerization of vinyl acetate and an ester compound, and the amount of polymerization initiator added. can do.

The adhesive of the present invention is obtained by mixing 100 parts by mass of the modified polyvinyl acetate, (A) 10 to 200 parts by mass of an organic solvent, and (B) 10 to 200 parts by mass of an inorganic filler.

(A) As an organic solvent used for the organic solvent adhesive, those usually used as a solvent for a polyvinyl acetate adhesive may be used. Methanol, ethanol, toluene, xylene, acetone, methyl ethyl ketone (MEK), n-hexane , Cyclohexane, methylcyclohexane, cyclopentane, isopropyl acetate and ethyl acetate. These organic solvents may be used alone or as a mixed solvent. As an organic solvent for the adhesive, it is desirable to use an organic solvent other than toluene, benzene and xylene, which are considered as chemical substances causing sick house syndrome, and it is desirable that a mixed solvent does not contain these.

The mixing amount of the organic solvent contained in the adhesive is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the modified polyvinyl acetate. By adjusting to this range, the coating property of the obtained adhesive can be improved, and the drying time of the adhesive does not become too long.

(B) The inorganic filler used in the inorganic filler adhesive may be one that is usually used as a filler for polyvinyl acetate adhesive, and is not particularly limited, but calcium carbonate, clay, kaolin, There are talc, silica, titanium oxide, hydrotalcite, mica and carbon black.

As for the compounding quantity of the inorganic filler contained in an adhesive agent, 10-200 mass parts is preferable with respect to 100 mass parts of modified polyvinyl acetate. By adjusting to this range, the viscosity and drying time of the adhesive obtained can be adjusted to a suitable range.

In order to obtain the adhesive, the modified polyvinyl acetate, the organic solvent, and the inorganic filler may be mixed using a stirring device such as a three-one motor.

<Example 1>
The modified polyvinyl acetate of Example 1 is composed of 92.3 mol% of a bond unit derived from vinyl acetate, 7.4 mol% of a bond unit derived from a fatty acid vinyl ester, and 0.3 mol of a bond unit derived from a monomer having a carboxyl group. %. The modified polyvinyl acetate of this example was excellent in alkali resistance. Moreover, the adhesive obtained using this was also excellent in adhesive strength.

Evaluation of the modified polyvinyl acetate and the adhesive was performed as shown below.
<Bonding unit amount>
The amount of bond units derived from vinyl acetate, the amount of bond units derived from a fatty acid vinyl ester, and the amount of bond units derived from a monomer having a carboxyl group in the modified polyvinyl acetate are calculated from the NMR measurement results of the modified polyvinyl acetate. Specifically, modified polyvinyl acetate is dissolved in deuterated methanol and measured using a 400 MHz proton NMR (JEOL ECX-400) at a temperature of 30 ° C. to obtain a measurement chart. From the obtained measurement chart, 1 .9 to 2.2 ppm peak (bond unit derived from vinyl acetate), 0.7 to 1.0 ppm peak (bond unit derived from fatty acid vinyl ester), 2.5 to 2.8 ppm (derived from a monomer having a carboxyl group) The content of each bond unit was calculated from the bond units).

<Average polymerization degree>
The average degree of polymerization of the modified polyvinyl acetate was measured according to “3.2 Average degree of polymerization” of JIS K6725-1977 “Testing method of polyvinyl acetate”.

<Alkali resistance>
The alkali resistance of the modified polyvinyl acetate was evaluated by the following procedure. 3 g of modified polyvinyl acetate is dissolved in 97 g of acetone, poured onto a film made of polytetrafluoroethylene, and dried at room temperature 23 ± 2 ° C. and humidity 50 ± 5% RH for 3 days to obtain a casting film having a thickness of 100 μm. . The obtained casting film is immersed in a 5% aqueous sodium hydroxide solution at 70 ° C. for 24 hours. The surface state of the cast film after the immersion is visually determined according to the following criteria.
A: No abnormality is observed.
◯: The surface is slightly white and cloudy.
X: Abnormalities such as whitening are observed.

<Tensile shear bond strength>
The tensile shear bond strength of the adhesive was measured according to JIS K-6850 “Test method for tensile shear bond strength of adhesive-rigid substrate”. ◎ when the entire adhesive layer is destroyed, ◯ when part of the adhesive layer is destroyed and partly peeled off at the interface between the adhesive layer and the adherend, and adhesive layer and adherend The case where the entire interface was peeled was marked with x.

As shown in Table 1, the modified polyvinyl acetate of Example 1 was 82.14 parts by mass of vinyl acetate, 17.33 parts by mass of vinyl laurate as a fatty acid vinyl ester, and maleic acid as a monomer having a carboxyl group. It is obtained by copolymerizing 0.53 parts by mass of monobutyl by suspension polymerization using 0.1 part by mass of dimethyl maleate-modified polyvinyl alcohol as an emulsifier.

Dimethyl maleate-modified polyvinyl alcohol was prepared according to the following procedure.
17 parts by weight of vinyl acetate, 14 parts by weight of methanol, 0.023 parts by weight of dimethyl maleate, 0.257 parts by weight of itaconic acid, and 0.10% azobisisobutyronitrile with respect to vinyl acetate were charged into a polymerization can. After nitrogen substitution, the temperature was raised to the boiling point, and a mixture of 6 parts by weight of vinyl acetate, 5 parts by weight of methanol and 0.207 parts by weight of dimethyl maleate was continuously added until the polymerization rate reached 75%. Polymerization was performed, and the polymerization was stopped when the polymerization rate reached 90%. Subsequently, unpolymerized vinyl acetate was removed by a conventional method, and the resulting polymer was saponified with sodium hydroxide by a conventional method. Thereafter, it was dried with hot air at 90 ° C. for 90 minutes to obtain a modified polyvinyl alcohol having a dimethyl maleate content of 0.6 mol%, a saponification degree of 88.0 mol%, and a molecular weight (Mn) of 11,000.

The above adhesive was prepared according to the following procedure.
An adhesive was obtained by mixing 50 g of modified polyvinyl acetate obtained by the above method, 50 g of methanol as an organic solvent, 20 g of calcium carbonate, 20 g of talc, and 10 g of silica as inorganic fillers using a three-one motor.

<Examples 2-1 to 2 >
In the modified polyvinyl acetates of Examples 2 to 12 , modified polyvinyl acetates were prepared in the same manner as in Example 1 by changing the types and amounts of the compounds used as described in Table 1 or Table 2. Example 1 It was evaluated in the same way. The evaluation results are shown in Table 1 or Table 2. The modified polyvinyl acetates of these examples were excellent in alkali resistance. Moreover, the adhesive obtained using this was also excellent in adhesive strength.

<Example 1 3-19>
Modified polyvinyl acetate of Example 1 3 to 19, the kind and amount of the compounds used to prepare a modified polyvinyl acetate in the same manner as in Example 1 was changed as described in Table 3, in the same manner as in Example 1 It has been evaluated. The evaluation results are shown in Table 3. The modified polyvinyl acetates of these examples were excellent in alkali resistance. Moreover, the adhesive obtained using this was also excellent in adhesive strength.

Diethyl maleate-modified polyvinyl alcohol used in Example 1 4 and 1 5 are those made in accordance with the following procedure.
17 parts by mass of vinyl acetate, 14 parts by mass of methanol, 0.023 parts by mass of diethyl maleate, and 0.10% azobisisobutyronitrile with respect to vinyl acetate were charged into the polymerization vessel, heated to the boiling point after nitrogen substitution. The temperature was raised, and a mixed solution of 6 parts by mass of vinyl acetate, 5 parts by mass of methanol and 0.207 parts by mass of diethyl maleate was continuously added until the polymerization rate reached 75%, and the polymerization rate was increased to 90%. When reached, the polymerization was stopped. Subsequently, unpolymerized vinyl acetate was removed, and the resulting polymer was saponified with sodium hydroxide. Thereafter, it was dried with hot air at 90 ° C. for 90 minutes, dimethyl mate maleate 0.6 mol%, saponification degree 88.0 mol%, molecular weight (Mn) 1
1000, 0.2% modified polyvinyl alcohol having an absorbance of 1.0 at a wavelength of 270 nm and an unmodified polyvinyl alcohol amount of 12% was obtained.

The unmodified polyvinyl alcohol used in Examples 16 and 17 was prepared according to the following procedure.
17 parts by mass of vinyl acetate, 14 parts by mass of methanol and 0.10% azobisisobutyronitrile with respect to vinyl acetate were charged into a polymerization can, heated after nitrogen substitution, and heated to the boiling point.
A mixed solution of 6 parts by mass of vinyl acetate and 5 parts by mass of methanol was continuously added until the polymerization rate reached 75%, and polymerization was performed. When the polymerization rate reached 90%, the polymerization was stopped. Subsequently, unpolymerized vinyl acetate was removed, and the resulting polymer was saponified with sodium hydroxide. Then 90 ° C
Drying with partial hot air yielded unmodified polyvinyl alcohol having a saponification degree of 88.0 mol% and a molecular weight (Mn) of 11,000.

<Comparative Examples 1-5>
The modified polyvinyl acetates in Comparative Examples 1 to 5 were prepared in the same manner as in Example 1 except that the types and amounts of the compounds used were changed as described in Table 4, and were evaluated in the same manner as in Example 1. It is a thing. The evaluation results are shown in Table 4. These modified polyvinyl acetates of Comparative Examples could not achieve the object of the present invention. In particular, the modified polyvinyl acetate of Comparative Example 5 could not be measured for alkali resistance because it did not dissolve in acetone. Moreover, since it did not melt | dissolve in methanol, the adhesive agent was not able to be created.

Claims (3)

Bond unit derived from vinyl acetate, 70 mol% to 92.3 mol%, and derived from fatty acid vinyl ester selected from vinyl caprylate, vinyl caprate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl neodecanoate A unit derived from a monomer having a unit of 5 mol% to 25 mol% and having a carboxyl group selected from acrylic acid, methacrylic acid, maleic acid, crotonic acid, maleic acid monoester, fumaric acid monoester and itaconic acid monoester 0 .Modified polyvinyl acetate having 1 mol% or more and 5 mol% or less. The modified polyvinyl acetate according to claim 1, wherein the average degree of polymerization is 1000 or more and 8000 or less. The adhesive agent which has 100 mass parts of modified polyvinyl acetates of Claim 1 or 2, 10-200 mass parts of organic solvents, and 10-200 mass parts of inorganic fillers.