JPS5914509B2 - hot melt adhesive - Google Patents

Description

[Detailed description of the invention] The present invention relates to water-soluble hot melt adhesives.

In recent years, hot melt adhesives have been used for bookbinding, packaging, woodworking,
It is increasingly being used for applications such as shoe making and textile bonding. Compared to other adhesives, it can be applied to a wide range of adherends, has a very fast bonding speed,
This is because there is no toxicity or fire hazard, and it is economically advantageous. Hot-melt adhesives are required to meet performance requirements such as adhesion, melt viscosity, heat resistance, cold resistance, and flexibility.For this reason, we have studied the formulation of adhesives using various polymers as a base. Ethylene-
Vinyl acetate copolymers, polyethylene, polypropylene, polyamides, polyesters, etc. are currently used as base polymers. Among the above uses, most of the hot melt adhesives for bookbinding are formulated based on ethylene-vinyl acetate copolymer, and have excellent adhesive properties.
Demand is rapidly increasing due to its excellent adhesive workability and flexibility, but since the resin is water and alkali resistant, it has become difficult to process waste wood into recycled paper. Currently, the spine with the mark attached is removed with a cutter to prevent it from getting mixed in. Because of this drawback, it is said that hot-melt adhesives for bookbinding cannot be expected to expand significantly.

In response to this, studies have recently been conducted focusing on the fact that partially saponified polyvinyl alcohol (hereinafter referred to as PVA)-based hot melt adhesives are easily dispersed or dissolved in water or dilute alkali, and the present applicant has also previously applied for a patent (Patent Application No. 50-76268).

5 In addition, JP-A-51-77632, 87041, 8
7542, 88533, 89538, 95440)96
There are many applications such as 831 and 96832. However, all of these are adhesives that have a low degree of polymerization and partially saponified PVA as the main ingredient, and contain a plasticizer, a so-called melt 30 viscosity reducer, a tackifier, etc.
For example, when used as an adhesive for bookbinding, the water dispersibility or water solubility during waste paper recycling is slow, so the adhesive remains in the pulp as small pieces, causing clogging of the screen 35 during the filtration process. Also, the particles that pass through the screen adhere to the wire mesh roll during paper making, causing pinholes in the paper, or adhere to the drying roll, causing paper breaks. Also, if it gets mixed into a product, it oozes out due to heat and forms spots, reducing the product value. In addition, when used as a label adhesive, there are problems such as the label being difficult to peel off when washing the bottle. However, the present inventors have determined that at least one of (meno)allylsulfonic acid, ethylenesulfonic acid, sulfonic acid (methio)acrylate, sulfonic acid malate, or an alkali salt thereof (hereinafter referred to as "for brevity")
We conducted extensive research focusing on the fact that modified PVA copolymerized with unsaturated sulfonic acid or its alkali salt has excellent water dispersibility and water solubility over a wide range of degrees of saponification and polymerization. , modification amount of unsaturated sulfonic acid or its alkali salt 0.3 to 7.0 mol%, degree of polymerization 30 to 6
001 It has been discovered that modified PVA adhesives made of modified PVA alone or mixed with a melt viscosity reducing agent with a degree of saponification of 0 to 80 mol % are excellent in hot melt adhesive workability, adhesion, and water dispersibility or water solubility. The present invention has now been completed.

As the alkali salt of the unsaturated sulfonic acid used in the present invention, sodium salt is practically most suitable.

Among these unsaturated sulfonic acids or alkali salts thereof, allylsulfonic acid or sodium allylsulfonate is particularly preferably used. Next, the modified PV used in the present invention
A typical manufacturing method for A is as follows. A method of copolymerizing 4-ethylene sulfonic acid, (meno)allylsulfonic acid, or an alkali salt thereof and vinyl acetate in an alcohol or an alcohol/water mixed solvent.

Or a method of further saponifying the copolymer. @ General formula CH2-C-CO-0-R'SO3MCR is hydrogen or a methyl group, R' is an alkylene group, M is hydrogen or an alkali metal] Sulfonic acid (meth)acrylate or its alkali salt and vinyl acetate A method of copolymerizing.

Or how to saponify this further. Specific examples of the sulfonic acid (meth)acrylate include 2-sulfonic acid ethyl (meth)acrylate, 2-sulfonic acid propyl (meno)acrylate, and alkali salts thereof. A method of copolymerizing sulfonic acid malate or an alkali salt thereof represented by CH-COO-R'SO3M [R1 is an alkyl group, R' and M are the same as O] and vinyl acetate.

Or how to saponify this further. Examples of the sulfonic acid malate include propyl 2-ethylhexyl sulfonate maleate, propyl tridecyl sulfonate maleate, propyl disulfonate maleate, and alkali salts thereof. The modified PVA used in the present invention is the above-mentioned unsaturated sulfonic acid or its alkali salt with a 0.3 to 7.
PVA with an average degree of polymerization of 30 to 600 and a degree of saponification of 0 to 80 mol% modified by 0 mol%, the amount of modification being 0.3
~7.0 mol%, preferably 1.0 to 5.0 mol%,
The average degree of polymerization is preferably 30 to 600, particularly preferably 80 to 500, and the saponification degree is preferably 0 to 80 mol%, particularly 0 to 70 mol% (that is, unsaponified products may be used).

If the amount of modification is less than 0.3 mol%, the water solubility is poor, and if the amount of modification is more than 7.0 mol%, the hygroscopicity of the adhesive increases and the adhesive strength decreases, so both are preferable. do not have. If the average degree of polymerization is less than 30, the adhesive strength will be insufficient, and if it is more than 600, the melt viscosity will be high and workability will be poor, so both are not preferred. The degree of saponification may be 0 mol %, that is, an unsaponified product, but if it is greater than 80 mol %, the melt viscosity is high, resulting in poor workability, which is not preferred.

However, in the case of an unsaponified product, it will not become water-soluble unless it is modified by 1.5 mol% or more with an alkali unsaturated sulfonic acid salt. Further, the vinyl alcohol portion of the modified PVA may be acetalized such as formalized or butyralized to an extent that does not impair water dispersibility or water solubility. Melt viscosity reducing agents used in the present invention include ethylene glycol, hexamethylene glycol, propylene glycol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol, xylitol,
Polyhydric alcohols such as arabite, adonite, mannite, solpit, and dulcitrate, their higher fatty acid esters, additives of these with ethylene oxide or propylene oxide, urea derivatives such as ethylene urea, phthalate esters (especially low Examples include those that have good compatibility with modified PVA, such as saponification degree (effective for modified PVA).

Furthermore, additives that can be incorporated into the adhesive of the present invention include rosins, rosin esters, etc., which have good compatibility with modified PVA, antioxidants, fillers, waxes, and the like. The modified PVA-based hot melt adhesive of the present invention can be used as a bookbinding adhesive (adhesive to the spine of perfect binding, cover to a covered cover, etc.) by taking advantage of its water-dispersible or water-soluble characteristics, and as an adhesive for box manufacturing ( Examples include flap stickers for cardboard, etc., and adhesives for temporary interlining of sewn clothing. Particularly when used as an adhesive for temporary interlining when sewing clothing, it can be used in powder form without the use of a melt viscosity reducing agent, and particles with a particle size of 10 to 150 mesh are preferred. It is. Next, the present invention will be explained with reference to Examples.

Example 1 Modified PVAlOO with a degree of polymerization of 230 and a degree of saponification of 52 mol% modified with sodium allylsulfonate at 2.5 mol%
(parts by weight, the same applies hereinafter), 45 parts of 10 mole ethylene oxide additive of Solpit, and 35 parts of mannitrate resin of polymerized rosin were melt-mixed in a mixer at 170°C to prepare an adhesive.

The obtained adhesive has a melt viscosity (BM type, Note (1) 180℃
, 30rpm) is 4800Cps1 Adhesive force is 4.2kg
/5cTn1 Water Solubility Note (2) was completely dissolved in 10 minutes and exhibited excellent properties in terms of hot and melt adhesive workability, adhesive strength, and water solubility.

Example 2 Modified PVA with a polymerization degree of 230 and a saponification degree of 0 mol% modified with 2.5 mol% sodium allylsulfonate, i.e. 100 parts of modified polyvinyl acetate, 20 parts of Solpit's 10 mol ethylene oxide adduct, polymerized An adhesive was prepared by melt-mixing 40 parts of rosin mannitridester resin and 20 parts of dibutyl fluorate at 170°C.

The obtained adhesive has a melt viscosity of 3500cpS1 adhesive strength of 4.1k9/5? The water solubility was completely dissolved in 10 minutes, and it exhibited excellent properties. Examples 3 to 5 In the same method as in Example 1, Example 3 uses PVA modified with 6.0 mol% of sodium allylsulfonate, and Example 4 uses PVA modified with 6.0 mol% of sodium allylsulfonate.
In Example 5, sodium sulfopropyl monobutyl maleate was used in the case of using mol% modified PVA.

The case where 5 mol% modified PVA is used will be described.

The measurement results are shown in Table 1. Example 6 Polymerization degree of 230, saponification degree of 52 mol%, modified PVA modified with sodium allylsulfonate of 2.5 mol% on a fabric made of Tetoron/cotton blend No. 16 single yarn of 95 yarns/inch
The particles with a particle size of 60 to 100 mesh were removed at a rate of 8y/a and dried for 35m in a hot air dryer set at 160℃.
The hot melt adhesive was temporarily fixed to the fabric by passing the hot melt adhesive at a speed of 1/2 min to create an interlining.

This interlining material was sandwiched between the front and lining of the jersey fabric for women's summer dresses, and the temperature was set at 130 to 150°C using a household 2-pound iron, and the pressure was 0.3 kg/cm.
Heat and pressure bonding was performed using Cd for 7 seconds. The peel strength of this adhesive interlining was 2807/(inch)2. Next is the Georgette table,
Three layers of lining fabric and interlining were sewn using a sewing machine, washed in a household washing machine with water at 40°C for 15 minutes, and washed with 2 layers of water.
After repeating the process several times, it was air-dried.

The peel strength of this sewn interlining was zero, and the glue was completely removed by washing with water. Also, the texture of the Georgette fabric was maintained. Control Example 1 An adhesive was prepared in the same manner as in Example 1 except that PVA with a degree of polymerization of 250 and a degree of saponification of 50 mol% was used in place of the modified PVA of Example 1. Melt viscosity is 500 compared to
Slightly high at 0cps, adhesive strength is 3.7k9/5Cr! L
The water solubility was small, and the water solubility was such that even after one day, it swelled but did not disperse or dissolve.

Therefore, it has a fatal drawback as a water-soluble hot melt adhesive. Control Examples 2 to 5 In Control Example 2, in the same method as Example 1, the modified amount of olefin sulfonic acid alkali salt was 10 mol%,
Control example 3 shows a case where the degree of polymerization is 20, Control example 4 shows a case where the degree of polymerization is 1000, and Control example 5 shows a case where the degree of saponification is 89 mol%.

The measurement results are shown in Table 1. Note (1) Adhesive strength: High quality paper
Cut it into 0 mwL x 50 mm, and apply adhesive in a linear shape with a width of about 3 mm at a distance of 20 mm from one end.

Cut cardboard that is then immediately cut to the same size. Overlap and glue.

The high-quality paper of this test piece was folded together from the adhesive part, the two sheets of paper and the cardboard part were set in an autograph, and the peel strength was determined at a tensile speed of 300 mm/mm and used as the adhesive strength.

Water solubility of adhesive: Small piece of adhesive (20 x 20 x 1 mm
) was immersed in water at 30°C and observed changes over time.

Claims (1)

[Claims] 1 (meth)allylsulfonic acid, ethylenesulfonic acid,
0.3 of at least one type (a) of sulfonic acid (meth)acrylate, sulfonic acid malate, or an alkali salt thereof
~7.0 mol% and vinyl acetate (b) at 99.7~93.
A modified polyvinyl alcohol-based hot melt adhesive comprising modified polyvinyl alcohol alone or mixed with a melt viscosity reducing agent having a degree of polymerization of 30 to 600 and a degree of saponification of 0 to 80 mol% copolymerized at a ratio of 0 mol%. 2. The adhesive according to claim 1, wherein the alkali salt of allylsulfonic acid is sodium allylsulfonate. 3. The adhesive according to claim 1, wherein the melt viscosity reducing agent is a mixture of an ethylene oxide adduct of a polyhydric alcohol and a higher fatty acid ester of a polyhydric alcohol.