CN104974688A - Expandable graphite-containing flexible anti-aging modified polyvinyl acetate emulsion adhesive for pencils and preparation method thereof - Google Patents

Abstract

The invention relates to the field of a polyvinyl acetate emulsion adhesive, specifically to an expandable graphite-containing flexible anti-aging modified polyvinyl acetate emulsion adhesive for pencils and a preparation method thereof. According to the preparation method of the adhesive, polymeric monomers such as vinyl acetate, acrylic acid and methyl acrylate, etc. react in nitrogen atmosphere and under the water-bath condition such that polymerization efficiency is higher; a modified guar gum solution is added during the reaction process to replace commonly-used polyvinyl alcohol so as to improve water resistance of the polymers; and the expandable graphite micro powder is added to effectively boost bond force of the adhesive and improve mechanical property of the adhesive layer. The modified polyvinyl acetate emulsion adhesive has good bond force on both timber and graphite cores, has toughness, is long-acting and anti-aging, and can be used to effectively protect graphite cores and reduce defective rate.

Description

A kind of pencil pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent containing expanded graphite and preparation method thereof

Technical field

The present invention relates to aqueous polyvinyl acetate emulsion sizing agent field, be specifically related to a kind of pencil pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent containing expanded graphite and preparation method thereof.

Background technology

Need to use sizing agent in pencil making processes, its effect is binded pencil-lead and pencil slat material, the sizing agent major part that product uses in the market is aqueous polyvinyl acetate emulsion sizing agent, this sizing agent raw material is cheap, easy to use, nontoxic, cohesive strength is higher, but also there are some shortcomings, shortcoming is mainly manifested in not water-fast, mechanical resistant poor stability, matter is crisp easy to crack, temperature tolerance haves much room for improvement, the polyvinyl acetate emulsion sizing agent of traditional performance shows as easy slide core when being applied on pencil, disconnected core, come unglued, the not problem such as Cutting free, directly have influence on the quality of product, therefore developing efficiently high-quality sizing agent is the vital link improving pencil quality.

Summary of the invention

The object of the present invention is to provide a kind of pencil pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent containing expanded graphite and preparation method thereof, prepared that a kind of mechanical property is good, water-tolerant, not easily embrittlement, novel aqueous polyvinyl acetate emulsion sizing agent that bond effect is good, to achieve these goals, the technical solution used in the present invention is as follows:

The pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent of a kind of pencil containing expanded graphite, it is characterized in that, this urea-formaldehyde resin adhesive is made up of the raw material of following weight part: vinyl acetate 48-54, vinylformic acid 12-14, methyl acrylate 6-8, Dry Flo PC 2-3,200-300 order expanded graphite powder 1-2, polydimethylsiloxane 1-2, guar gum 10-12, OP-10 4-5, sodium lauryl sulphate 1.2-1.6, Potassium Persulphate 0.4-0.5,10% sodium hydroxide solution is appropriate, acetic acid solution is appropriate, ammoniacal liquor is appropriate, deionized water 220-250;

The preparation method of described modified polyvinyl acetate emulsion sizing agent comprises following steps:

(1) first guar gum, Dry Flo PC, sodium lauryl sulphate are dropped in the deionized water of 30-40 weight part, be heated to 70-80 DEG C, high-speed stirring adds 10% sodium hydroxide solution after making it dissolve completely, regulator solution pH value is 9.5-10.0, add polydimethylsiloxane after continuing to be uniformly mixed, continue to be uniformly mixed 50-60min, be cooled to 50-60 DEG C subsequently, dripping acetic acid regulator solution pH value is 7.8-8.0, obtains modified guar solution for standby;

(2) modified guar solution step (1) prepared, the OP-10 of 2/3 weight part and other leftover materials except Potassium Persulphate mix with the deionized water of 50-60 weight part, at 45-50 DEG C, constant temperature high-speed stirring mixing 2-3h, obtains pre-emulsification mixed solution for subsequent use;

(3) surplus OP-10 is dissolved in the deionized water of surplus, drop in reaction vessel, and in container, pass into nitrogen removing oxygen, then the pre-emulsification mixed solution of 1/3 weight part is added, and heating in water bath is to 60-65 DEG C, add the Potassium Persulphate of 0.1-0.2 weight part subsequently, isothermal reaction 30-40min, then remaining pre-emulsification mixed solution is dripped with the speed of 0.04-0.05g/min, add remaining Potassium Persulphate simultaneously, under 60-65 DEG C of condition, 150-180min is incubated after dropwising, be cooled to less than 45 DEG C subsequently, drip ammoniacal liquor adjust ph to be 7.0-7.5 and to get final product.

Beneficial effect of the present invention is:

First the present invention starts with from experimental installation, letting nitrogen in and deoxidizing in reaction vessel, gets rid of the interference of oxygen, improves the polymerization efficiency of monomer, improves productive rate, and whole reaction process is carried out in a water bath simultaneously, whole reaction system is heated evenly, reacts more efficient; In addition the guar gum solution replacing for polyvinyl alcohol of the present invention's modification; effectively improve the not water tolerance of polymerisate; the expanded graphite micro mist added effectively raises the stiction force of emulsion; improve the mechanical property of glue-line; modified polyvinyl acetate emulsion sizing agent prepared by the present invention all has good cohesive force, good toughness to timber and graphite core, long-acting anti-aging; energy available protecting graphite core, reduction in the numbers of seconds.

Embodiment

Embodiment

The sizing agent of the present embodiment is made up of the raw material of following weight part: vinyl acetate 50, vinylformic acid 12, methyl acrylate 6, Dry Flo PC 3,300 order expanded graphite powder 1.5, polydimethylsiloxane 1.8, guar gum 12, OP-10 5, sodium lauryl sulphate 1.5, Potassium Persulphate 0.5,10% sodium hydroxide solution is appropriate, acetic acid solution is appropriate, ammoniacal liquor is appropriate, deionized water 230.

The preparation method of this sizing agent is:

(1) first guar gum, Dry Flo PC, sodium lauryl sulphate are dropped in the deionized water of 40 weight parts, be heated to 75 DEG C, high-speed stirring adds 10% sodium hydroxide solution after making it dissolve completely, regulator solution pH value is 9.8, add polydimethylsiloxane after continuing to be uniformly mixed, continue to be uniformly mixed 60min, be cooled to 50 DEG C subsequently, dripping acetic acid regulator solution pH value is 8.0, obtains modified guar solution for standby;

(2) modified guar solution step (1) prepared, the OP-10 of 2/3 weight part and other leftover materials except Potassium Persulphate mix with the deionized water of 55 weight parts, at 45 DEG C, constant temperature high-speed stirring mixing 2.5h, obtains pre-emulsification mixed solution for subsequent use;

(3) surplus OP-10 is dissolved in the deionized water of surplus, drop in reaction vessel, and in container, pass into nitrogen removing oxygen, then the pre-emulsification mixed solution of 1/3 weight part is added, and heating in water bath to 60 DEG C, add the Potassium Persulphate of 0.2 weight part subsequently, isothermal reaction 30min, then remaining pre-emulsification mixed solution is dripped with the speed of 0.05g/min, add remaining Potassium Persulphate simultaneously, under 60 DEG C of conditions, be incubated 160min after dropwising, be cooled to less than 45 DEG C subsequently, drip ammoniacal liquor adjust ph and be 7.4 and get final product.

Performance test results after the bonding pencil of product application obtained by the present embodiment is as follows:

Be 1.0% by the average slide core rate of the pencil that this modified polyvinyl acetate sizing agent is bonding, cutting average core-breaking rate in a process is 0.6%, after the water soaking 1h of 40 ± 5 DEG C, on average the rate of coming unglued is 2.8%, all lower than traditional aqueous polyvinyl acetate emulsion sizing agent, and its ageing cycle in-20-50 DEG C of temperature range on average comes unglued rate for 3 times afterwards lower than 1.5%, bind time average completely and shorten 10.2h.

Claims (2)

1. the pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent of a pencil containing expanded graphite, it is characterized in that, this sizing agent is made up of the raw material of following weight part: vinyl acetate 48-54, vinylformic acid 12-14, methyl acrylate 6-8, Dry Flo PC 2-3,200-300 order expanded graphite powder 1-2, polydimethylsiloxane 1-2, guar gum 10-12, OP-10 4-5, sodium lauryl sulphate 1.2-1.6, Potassium Persulphate 0.4-0.5,10% sodium hydroxide solution is appropriate, acetic acid solution is appropriate, ammoniacal liquor is appropriate, deionized water 220-250.

2. a kind of pencil preparation method of the pliable and tough anti-aging modified polyvinyl acetate emulsion sizing agent containing expanded graphite as claimed in claim 1, is characterized in that, comprise following steps:

(1) first guar gum, Dry Flo PC, sodium lauryl sulphate are dropped in the deionized water of 30-40 weight part, be heated to 70-80 DEG C, high-speed stirring adds 10% sodium hydroxide solution after making it dissolve completely, regulator solution pH value is 9.5-10.0, add polydimethylsiloxane after continuing to be uniformly mixed, continue to be uniformly mixed 50-60min, be cooled to 50-60 DEG C subsequently, dripping acetic acid regulator solution pH value is 7.8-8.0, obtains modified guar solution for standby;

(2) modified guar solution step (1) prepared, the OP-10 of 2/3 weight part and other leftover materials except Potassium Persulphate mix with the deionized water of 50-60 weight part, at 45-50 DEG C, constant temperature high-speed stirring mixing 2-3h, obtains pre-emulsification mixed solution for subsequent use;

(3) surplus OP-10 is dissolved in the deionized water of surplus, drop in reaction vessel, and in container, pass into nitrogen removing oxygen, then the pre-emulsification mixed solution of 1/3 weight part is added, and heating in water bath is to 60-65 DEG C, add the Potassium Persulphate of 0.1-0.2 weight part subsequently, isothermal reaction 30-40min, then remaining pre-emulsification mixed solution is dripped with the speed of 0.04-0.05g/min, add remaining Potassium Persulphate simultaneously, under 60-65 DEG C of condition, 150-180min is incubated after dropwising, be cooled to less than 45 DEG C subsequently, drip ammoniacal liquor adjust ph to be 7.0-7.5 and to get final product.