JP2000001514A - Production of polyvinyl acetal resin, polyvinyl acetal resin produced thereby, and interlayer for laminated glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyvinyl acetal resin used for e.g. an interlayer for a laminated glass and having excellent adhesiveness by selecting a polyvinyl acetal resin having a specified or lower content of divalent metals. SOLUTION: This resin has a content of divalent metals of 30 ppm or below. This is obtained by using water having a content of divalent metals of 10 ppm or below in the production of the resin by reacting polyvinyl alcohol with an aldehyde. The water used includes at least water used to dissolve the polyvinyl alcohol used as the starting material and used to react it with the aldehyde, water used for washing the polyvinyl acetal resin after the reaction, and water used to precipitate the polyvinyl acetal in a solvent process and a homogeneous system process. More desirably, it includes any water that is to come into contact with parts with which the starting materials and the obtained polyvinyl acetal resin contact in the entire course of an acetal production process including the dissolution of a polyvinyl alcohol, its acetalization, neutralization, dehydration, washing, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyvinyl acetal resin having improved adhesiveness when used for laminated glass, a polyvinyl acetal resin produced by the method, and an intermediate for laminated glass using the same. About the membrane.

[0002]

2. Description of the Related Art Polyvinyl acetal resins are widely used as raw materials for intermediate films of safety glass, paints, adhesives and the like. Polyvinyl acetal resin is manufactured by various methods, but is mainly manufactured by a method called an aqueous medium method. In this method, an aldehyde is added to an aqueous solution of polyvinyl alcohol in the presence of an acid catalyst, and acetalization is performed. Initiate the reaction. With the progress of acetalization, a precipitate is formed, and thereafter, the reaction proceeds in a heterogeneous system. Aldehyde addition is generally performed at a relatively low temperature of 20 ° C. or lower, and then the temperature is raised to perform an aging reaction at 40 ° C. or higher. After completion of the reaction, neutralization is performed with an alkali. To remove impurities,
Washing and dehydration are repeated, purified, dried and commercialized. Other than the aqueous medium method, there are manufacturing methods such as a solvent method and a homogeneous method.

[0003] The polyvinyl acetal resin obtained by the above manufacturing method is suitably used for manufacturing an interlayer film for laminated glass. This laminated glass is widely used for various transportation means such as automobiles and airplanes, and windows of buildings.
In general, two plate-like glasses laminated using an intermediate film made of plasticized polyvinyl acetal resin are used.

[0004] The laminated glass has such a property that even if the glass is broken when an impact is applied thereto, the interlayer film interposed between the glass is not easily broken but absorbs the shock. Things do not easily penetrate,
The glass bonded by the intermediate film remains adhered to the intermediate film even after the breakage, so that the fragments are not scattered, thereby significantly injuring a human body in a transportation or a building. There is no.

[0005] However, in order to protect the human body more safely against an external impact, the above-mentioned situation requires that the interlayer film used should have performances in accordance with the intended use in terms of adhesion and penetration resistance. Have been.

As described above, as a method of adjusting the adhesiveness and the penetration resistance, in addition to the conventional methods of changing the film thickness and adjusting the water content in the intermediate film,
Various adhesive modifiers have been studied, and alkali metal, alkaline earth metal salts and the like have been mainly proposed (for example,
See Japanese Patent Publication No. 44-32183).

However, various methods for adjusting the adhesive force have been proposed by the above-mentioned methods. However, since the adhesive force varies depending on the polyvinyl acetal resin, the amount of adjustment must be adjusted each time in order to produce an intermediate film having stable quality. Had to be changed.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has as its object to provide a polyvinyl acetal resin having excellent adhesiveness used for an interlayer film for laminated glass and the production thereof. It is an object of the present invention to provide a method and an interlayer film for a laminated glass having excellent adhesiveness, easy adjustment of the adhesive force and stability as a laminated glass.

[0009]

As a result of various studies, the present inventor has found that by controlling the content of a divalent metal contained in water used in the production of polyvinyl acetal, a polyvinyl acetal resin having excellent adhesiveness can be obtained. Can be manufactured, and the interlayer film for laminated glass using it is extremely excellent in adhesiveness,
And found that the adhesive force was easy to adjust and stable,
The present invention has been completed.

That is, the present invention relates to a polyvinyl acetal resin having a divalent metal content of 30 ppm or less, a method of reacting polyvinyl alcohol with an aldehyde to produce a polyvinyl acetal resin, and the water used for the production in the production of the polyvinyl acetal resin. For producing a polyvinyl acetal resin using water having a content of 10 ppm or less, a polyvinyl acetal resin having a divalent metal content of 30 ppm or less obtained by the production method, and a laminated glass using these polyvinyl acetal resins. It is an intermediate film.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The water used in the production of the present invention is at least water used for dissolving polyvinyl alcohol, which is a raw material of polyvinyl acetal, and reacting with aldehyde, water used for washing the polyvinyl acetal resin for purification after completion of the reaction, and a solvent method. In the homogeneous method, it refers to water used to precipitate polyvinyl butyral. More preferably, dissolution of polyvinyl alcohol, acetalization reaction, neutralization,
It refers to all the raw materials in the acetal production process such as dehydration and washing, and all the water in contact with the obtained polyvinyl acetal resin.

The divalent metal in the water used for the production is 10 pp
m or less. 10 content of divalent metal
When the content exceeds ppm, calcium and magnesium are contained in a large amount in the obtained polyvinyl acetal, and the quality such as adhesiveness is deteriorated. In addition, the interlayer film for laminated glass using the obtained polyvinyl acetal resin has a problem that the adhesive strength represented by the Pummel value is significantly reduced.

The polyvinyl acetal resin of the present invention has a divalent metal content of 30 ppm or less. Here, the divalent metal generally refers to calcium and magnesium mainly contained in river water and well water. 30p divalent metal content
If it exceeds pm, the quality such as adhesiveness deteriorates. In addition, the interlayer film for laminated glass using the obtained polyvinyl acetal resin has a problem that the adhesive strength represented by the Pummel value is greatly reduced.

As described above, the polyvinyl acetal resin has a function of taking in the divalent metal in the water to be used into the resin by a certain action. The result remains inside. When such a resin is purified, the interlayer film for laminated glass manufactured using the same has a large change in surface state, such as an increase in moisture on the surface as compared with a case where the content of the divalent metal is small, and the glass state Greatly reduces the adhesive strength with the adhesive.

[0015] Acetalization of polyvinyl alcohol includes an aqueous medium method, a solvent method, and a homogenization method, but the present invention is not limited thereto. (1) Water medium method: Polyvinyl alcohol is dissolved in hot water,
The resulting aqueous solution is kept at a relatively low temperature of 20 ° C. or lower, and an acid catalyst is added thereto, aldehyde is added with stirring, and the acetalization reaction is allowed to proceed. This is a method of aging at a high temperature of not less than ° C. to complete the reaction, followed by neutralization, washing, dehydration and drying. (2) Dissolution method: polyvinyl alcohol powder is suspended in a solvent of polyvinyl acetal, aldehyde is added in the presence of an acid catalyst, and an acetalization reaction is started. As the acetalization proceeds, the reactants are dissolved in the solvent, and then the reaction proceeds in a homogeneous system. After completion of the reaction, the reaction is neutralized, water is added, and the mixture is precipitated, followed by washing, dehydration and drying. (3) Homogeneous method: In the presence of an acid catalyst, an aldehyde is added to an aqueous polyvinyl alcohol solution to start an acetalization reaction. Before the precipitation, a water-compatible polyvinyl acetal solvent is added to form a precipitate. The reaction proceeds in a homogeneous system throughout while preventing precipitation. After completion of the reaction, the reaction is neutralized, water is added, and the mixture is precipitated, followed by washing, dehydration and drying.

The polyvinyl alcohol used in the present invention is not particularly limited, and commercially available ones can be used. Examples thereof include polymers of fatty acid vinyl esters such as vinyl acetate, and the like.
The copolymer having an average degree of polymerization of about 200 to 4000 obtained by completely or partially saponifying the copolymer is generally used.

Aldehydes used in the reaction for acetalizing polyvinyl alcohol include, for example, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, benzaldehyde, and the like. The polyvinyl acetal obtained by coexisting with the reaction system for the conversion can also be used in the present invention. Upon completion of the acetalization reaction, the acid catalyst is generally neutralized with an alkaline substance, but may be reacted with an alkylene oxide.

In the polyvinyl acetal resin and the method for producing the same according to the present invention, substances such as antioxidants and surfactants can be optionally used, if necessary.

As a method for producing the interlayer film for laminated glass of the present invention, a plasticizer, an ultraviolet absorber, a stabilizer and the like are added to the polyvinyl acetal resin obtained by the above method, and the mixture is kneaded well at 80 to 100 ° C. It is manufactured as a sheet-like molded product by pressing or extruding at 140 ° C.

In the interlayer film for laminated glass of the present invention,
As the plasticizer, those usually used as plasticizers for plastics can be used. However, in the polyvinyl acetal composition, an ester plasticizer having an ether bond in a molecule [triethylene glycol di-2-ethyl] is used. Butyrate, triethylene glycol di-2-ethylhexanoate, di (butoxyethoxyethyl) adipate,
Di-n-hexyl adipate] is preferred. As the ultraviolet absorber, those commonly used for plastics can be used, but benzotriazole-based ultraviolet absorbers [2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2 '-Hydroxy-
3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole and the like]. A hindered amine-based light stabilizer may be added as needed.

The interlayer for laminated glass of the present invention desirably has an adhesive strength to a laminated glass plate within an appropriate range, and more preferably has a Pummel value of 6 to 10.

[0022]

The present invention will be specifically described below with reference to examples and comparative examples. In the following, unless otherwise specified,
“Parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Example 1 (Production of polyvinyl acetal resin) 100 parts of polyvinyl alcohol having an average degree of polymerization of 1700 and a saponification degree of 98.5 mol% were mixed with 900 parts of a reaction vessel equipped with a temperature controller and a stirrer. Was heated and dissolved in ion-exchanged water (Ca, Mg content: 1 ppm each). The aqueous solution was kept at 10 ° C. while stirring was continued, and 60 parts of 35% hydrochloric acid was added thereto. Then, 57 parts of butyraldehyde were continuously added and mixed for 30 minutes. 15 minutes after the start of the addition, polyvinyl butyral particles were precipitated in the reaction solution. Thereafter, the temperature of the reaction system was raised to 40 ° C. with stirring and maintained for 4 hours. After the reaction,
The system was neutralized by the addition of aqueous sodium hydroxide and cooled to room temperature. Furthermore, after filtering the slurry,
After washing with ion-exchanged water of the same grade as described above, filtration, drying and the like were performed to obtain polyvinyl butyral as a white powder. Ca in the obtained polyvinyl butyral resin
And Mg content were 5 ppm and 4 ppm, respectively. (Production of interlayer film for laminated glass) 100 parts of this polyvinyl butyral resin was added with 2- (2'-
0.2 part of (hydroxy-5'-methylphenyl) benzotriazole and 35 parts of di-n-hexyl adipate as a plasticizer were mixed. The resulting mixture was well kneaded with a two-roll heated to 85 ° C. The obtained sheet-like molded product was heated and pressurized to 140 ° C. by a press regulated by a spacer to obtain an interlayer film for laminated glass having a thickness of 0.8 mm.

Example 2 A polyvinyl butyral resin and an interlayer film for laminated glass were produced in the same manner as in Example 1, except that water containing 4 ppm of Ca and 4 ppm of Mg was used as water for production. Ca and M in polyvinyl butyral resin
The content of g was 22 ppm and 7 ppm, respectively.

Comparative Example 1 An intermediate film for a polyvinyl butyral resin and a laminated glass was produced in the same manner as in Example 1 except that water containing 10 ppm of Ca and 2 ppm of Mg was used as water for production. The contents of Ca and Mg in the polyvinyl butyral resin were 94 ppm and 10 ppm, respectively.

Comparative Example 2 As water for dissolving polyvinyl alcohol,
Example 1 except that water containing m, Mg 2 ppm was used.
Was carried out in the same manner as described above to produce a polyvinyl butyral resin and an interlayer film for laminated glass. The content of Ca and Mg in the polyvinyl butyral resin was 48 ppm,
It was 8 ppm.

Comparative Example 3 Polyvinyl butyral was used as water for washing
Example 1 except that water containing m, Mg 2 ppm was used.
Was carried out in the same manner as described above to produce a polyvinyl butyral resin and an interlayer film for laminated glass. The content of Ca and Mg in the polyvinyl butyral resin was 66 ppm,
It was 10 ppm.

Example 3 (Pummel test) The interlayer films obtained in Examples and Comparative Examples were sandwiched from both sides with two pieces of float glass having a length of 70 mm, a width of 105 mm and a thickness of 2 mm, and were preliminarily bonded by a roll method. Then, the autoclave at 140 ° C. was 12 kg / cm 2
At a pressure of 30 minutes to obtain a transparent laminated glass.
The laminated glass was left at −18 ° C. for about 16 hours, placed on a flat table, and placed on a 1.5-pound hammer for 15 hours.
It was hit 50 times at an angle of 45 ° C. from the top of the cm. The state of the film after the glass was partially exfoliated was compared with a pre-rated limit sample (0 when the film surface was completely exposed, and 10 when the film surface was barely exposed) to determine the adhesiveness. Table 1 shows the results.

[0029]

[Table 1]

[0030]

Industrial Applicability According to the present invention, a polyvinyl acetal resin having excellent adhesiveness used for an interlayer film for laminated glass and the like, a method for producing the same, and a laminated glass having excellent adhesiveness, easy adjustment of adhesive strength and stability. An interlayer for laminated glass is provided.

Continued on the front page F-term (reference) 4F100 AG00B AG00C AK23A BA03 BA06 BA10B BA10C CA07A GB07 GB31 GB32 JL11A 4G061 AA02 BA01 BA02 CB18 CB19 CD02 CD18 4J040 DD071 HA126 JA09 LA06 MA05 QA01 4J100 AD02P AF16P HC17 BC17 HC17 BC17 HC21 HE12 HE41 JA03 JA05

Claims (4)

[Claims] 1. A polyvinyl acetal resin having a divalent metal content of 30 ppm or less and excellent in adhesiveness. 2. A method for producing a polyvinyl acetal resin by reacting polyvinyl alcohol with an aldehyde, wherein the water used in the production has a divalent metal content of 1%.
A method for producing a polyvinyl acetal resin having excellent adhesion, wherein 0 ppm or less of water is used. 3. The polyvinyl acetal resin according to claim 1, produced by the method according to claim 2. 4. An interlayer film for laminated glass using the polyvinyl acetal resin according to claim 1 or 3.