JP2000256643A - Production of particulate hot-melt adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the blocking of adhesive particles and get rid of the interruption of feeding in an automatic feeding line due to the blocking by controlling the temperature of the adhesive composition heated in the extruder below a specified value in a process wherein an adhesive composition is heated, kneaded and extruded through an extruder in a rod form and then cut under cooling to form spherical particles. SOLUTION: A hot-melt adhesive composition heated, kneaded and extruded through an extruder is cut under cooling in a cooling water tank to form into a spherical form, wherein the temperature of the composition heated in the extruder is 125 deg.C or lower. It is desirable that the elastic modulus of the adhesive composition at the temperature in the extruder is 50-5,000 Pa and that the difference between the temperature of the composition heated in the extruder and the temperature of water in the cooling water tank is within 115 deg.C. The composition can be formed in a spherical form close to true sphere and excellent in fluidity by controlling the difference within 115 deg.C, even when the melt viscosity of the composition at 180 deg.C is 1,100 cPs or lower. This adhesive may contain a thermoplastic resin and, if necessary, additives such as a tackifier resin and a wax.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a granular hot-melt adhesive, and more particularly to a method for producing a granular hot-melt adhesive with less blocking of the granular hot-melt adhesive.

[0002]

2. Description of the Related Art Hot-melt adhesives are widely used in the paper and wood fields, especially in the paper and wood fields, without using solvents having troublesome properties such as flammability, leakiness and permeability. However, due to the property of hot-melt adhesives that develops adhesiveness when heated, the hot-melt adhesive formed into granular or other shapes at each stage of its manufacture, storage, transportation, and use. There is a disadvantage that the melt adhesives block each other and it is difficult to take out the hot melt adhesive in each step.

Conventionally, various methods have been proposed as attempts to prevent blocking between hot melt adhesives. For example, JP-A-3-121176 discloses that a hot-melt adhesive having a softening point higher than room temperature and having tackiness at room temperature is composed of a thermoplastic organic polymer dispersion, an emulsion, and an aqueous solution in a molten state. A method is disclosed in which each piece is extruded into water containing an anti-adhesive agent and cut into individual pieces by cutting with a cutter that can be cut continuously, such as a rotary blade.

However, in the method for forming a hot-melt adhesive described above, the preferable temperature of the cooling water containing the anti-adhesive is 2 ° C.
Since the hot melt adhesive in a molten state is rapidly cooled and solidified and then cut by a cutter because it is extremely low and rapidly cooled down to -20 ° C., the resulting hot melt adhesive is composed of fragments. Is a cylindrical shape having a central axis longer than the diameter of the cross section from a disk shape depending on the rotation speed of the cutter, and a fragment composed of a mixture of these crushed pieces.

Furthermore, these fragments have constrictions, or have irregularities such as dents and projections on the surface thereof, and have a relatively large surface area per unit volume. In addition, it has poor lubricity and poor fluidity in pneumatic transportation, and when the hot melt adhesive is supplied to the hopper of the applicator to some extent intermittently by automatic transportation of a pneumatic feeder, etc. Thus, there is a problem that a so-called bridge is formed at a supply port due to blocking between the hot melt adhesives and supply of the hot melt adhesive to the machine is interrupted. The above tendency is that when the machine is stopped, such as when the machine is restored for trouble or when the workers are taking a break, the hot melt adhesive always causes the blocking, the supply is interrupted, and in the case of unmanned machines etc., a large amount of defective bonding products are discharged. Etc.
The effect of the supply interruption was significant.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and has as its object to form a hot melt adhesive by forming a hot melt adhesive cut piece into a spherical shape. It is an object of the present invention to provide a method for producing a granular hot melt adhesive which prevents blocking between each other and has no supply interruption caused by blocking in an automatic supply line.

[0007]

According to a first aspect of the present invention, there is provided a method for producing a granular hot-melt adhesive, wherein the hot-melt adhesive composition extruded into a rod shape by heating and kneading with an extruder is cooled in a cooling water tank. A method for producing a granular hot melt adhesive which is cut below and formed into a sphere, wherein the heating temperature of the hot melt adhesive composition which is heated and kneaded by an extruder and extruded into a rod shape is 125 ° C. or less. And

According to a second aspect of the present invention, there is provided the method for producing a granular hot melt adhesive according to the first aspect of the present invention, wherein the elasticity of the hot melt adhesive composition at the temperature in the extruder is obtained. The rate is 50 to 5000 Pa.

The method for producing a granular hot melt adhesive according to the third aspect of the present invention is characterized in that the hot melt adhesive composition extruded into a rod shape by heating and kneading with an extruder is cut under cooling in a cooling water bath to form a spherical shape. A method for producing a granular hot melt adhesive to be molded, wherein a difference between a heating temperature in an extruder and a water temperature in a cooling water tank is within 115 ° C.

The method for producing a granular hot melt adhesive according to the invention according to claim 4 is the method for producing a granular hot melt adhesive according to claim 1, wherein the melt viscosity of the hot melt adhesive composition at 180 ° C. Is 1100 cps or less.

The granular hot melt adhesive used in the present invention comprises a thermoplastic resin containing additives such as a tackifier resin and waxes as required. Examples of the thermoplastic resin include, but are not particularly limited to, for example, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, atactic polypropylene which becomes liquid at a temperature of 50 to 200 ° C,
Amorphous poly (α-olefin) and the like can be mentioned.
These thermoplastic resins may be used alone,
Two or more kinds may be used in combination.

Examples of the tackifying resin include natural resins which are commercially available under the trade names such as gum rosin, wood rosin, tall oil rosin; modified rosins such as polymerized rosin and partially hydrogenated rosin; glycerin ester rosin; Hydrogenated rosin, fully hydrogenated rosin or polymerized rosin,
Derivatives of rosin and modified rosin, such as pentaerythritol ester and partially hydrogenated rosin, fully hydrogenated rosin or polymerized rosin; polymers of α-pinene, β-
Polyterpene-based resins such as polymer of pinene and dipentene; modified terpenes such as terpene-phenol copolymer and α-pinene-phenol copolymer; aliphatic petroleum resin;
Alicyclic petroleum resin; cyclopentadiene resin; aromatic petroleum resin; phenolic resin; alkylphenol-acetylene resin; styrene resin; xylene resin; cumarone indene resin; vinyl toluene, α-methylstyrene copolymer, etc. Is mentioned.

The above waxes include, for example, carnauba wax, montan wax, paraffin wax,
Examples include microcrystalline wax, and particularly, waxes in which at least one of the waxes is a paraffin wax or a Fischer-Tropsch wax containing 85% by weight or more of an n-paraffin component is preferably used.

If necessary, the granular hot melt adhesive may contain, for example, an antioxidant, an ultraviolet absorber, a filler,
An additive such as a coloring agent may be contained.

The means for producing the granular hot melt adhesive used in the present invention is not particularly limited.
For example, there is a method in which each of the above-mentioned materials is heated and kneaded using a melting tank, a roll, a Banbury mixer, a kneader, an extruder, or the like, and mixed.

The production apparatus used in the method for producing a granular hot-melt adhesive of the present invention is not particularly limited, but the hot-melt adhesive composition is heated and kneaded.
It comprises an extruder for extruding into a rod, a granulator for cutting the hot-melt adhesive composition extruded into a rod under cooling in a cooling water tank, and molding into a sphere, and these accessories.

The extruder is capable of heating and kneading the hot-melt adhesive composition and extruding the hot-melt adhesive composition into a rod shape, and has a control mechanism capable of maintaining the heating temperature of the hot-melt adhesive composition at 125 ° C. or lower. There is no particular limitation as long as it is attached, but examples thereof include a plunger type extruder, a screw type extruder, and a gear pump type extruder. These extruders may be used alone, but extruders combining the respective extruding functions may be used.

The mold for extruding the hot-melt adhesive composition into a rod shape may be a mold having only one mold cavity, but a mold having a plurality of mold cavities may be used. It is preferably used to increase productivity. The shape of the mold cavity is
There is no particular limitation, for example, a cross section of a triangle, a square,..., A polygon, a circle, etc., but the cross section is easy to make the shape of the granular hot melt adhesive close to a true sphere and easy to maintain the apparatus. A circular mold cavity is preferably used.

The granulator is not particularly limited as long as it cuts and granulates the hot-melt adhesive composition extruded in a rod shape in a cooling water tank under cooling. As shown in FIG. 1 and FIG.
Hot-melt adhesive composition 2 extruded into a rod from 2
The rotating blade 31 (rotating blade 31 may be a single blade or a plurality of rotating blades) may be rotated in proximity to the mold in parallel with a plane perpendicular to the extrusion direction. Rotary blade 3
1 is attached to a mounting plate 32, and a rotational force is transmitted to the mounting plate 32 by a driving shaft 33). The cutting device 3 cuts the cutting device 3 into particles, and the cutting device 3 and the surface of the mold 12 are wrapped. And a granulator including a cooling water tank 4, a cooling water supply device 41, a drainage / granular hot melt adhesive discharging device 42, a granular hot melt adhesive separating device 5, and the like.

The method for producing a granular hot melt adhesive of the present invention is carried out using a production apparatus as shown in FIG. 1. Preferably, the cut length of the hot melt adhesive composition extruded in a rod shape is The mold cavity is cut to a length substantially equal to the diameter of the cross section of the mold cavity. The particle size of the obtained granular hot melt adhesive is not particularly limited, but if it is too small, the fluidity in pneumatic transportation decreases, and if it is too large, handleability deteriorates. A slightly larger one is preferably used.

In the method for producing a granular hot-melt adhesive according to the first aspect of the present invention, if the heating temperature of the hot-melt adhesive composition heated and kneaded by an extruder and extruded into a rod shape exceeds 125 ° C., The resulting granular hot-melt adhesive is liable to be constricted or uneven on the surface due to deformation after extrusion, and it is difficult to form the spherical hot-melt adhesive into a spherical shape close to a true sphere having excellent fluidity.

In the method for producing a granular hot melt adhesive according to the present invention, if the elastic modulus of the hot melt adhesive composition used at the temperature in the extruder is less than 50 Pa, the obtained granular hot melt adhesive is obtained. When constriction or unevenness of the surface occurs and exceeds 5000 Pa, the stress for expanding the tip of the hot-melt adhesive composition extruded in a rod shape does not sufficiently appear, and the shape is changed from a disc shape to a column shape. It is cut as it is extruded as it is, and in some cases, distortion due to heat shrinkage occurs due to the difference in cooling rate between the surface and the inside, etc. It becomes difficult to form a sphere close to a sphere. The elastic modulus of the hot melt adhesive composition used at the temperature in the extruder is
Preferably 100 to 4500 Pa, more preferably 20
0 to 4000 Pa. The temperature in the extruder is preferably a temperature measured at the time of melt extrusion.

In the method for producing a granular hot melt adhesive according to the present invention, if the difference between the heating temperature in the extruder and the water temperature in the cooling water tank exceeds 115 ° C., the hot melt adhesive composition extruded in a rod shape is obtained. Since the stress that tends to expand the tip of the product is not sufficiently developed, the resulting granular hot melt adhesive is cut while being extruded from a disk shape to a cylindrical shape, and in some cases, the internal and external cooling rates As a result, a depression with a depressed surface is generated, and it is difficult to form a sphere close to a true sphere having excellent fluidity. The difference between the heating temperature in the extruder and the water temperature in the cooling water tank is preferably 90 ° C. or less, more preferably 70 ° C. or less.

In the method for producing a granular hot melt adhesive according to the present invention, if the melt viscosity at 180 ° C. of the hot melt adhesive composition used is 1100 cps or less, the melt viscosity is low. The stress to expand the tip of the hot-melt adhesive composition is not sufficiently developed, and the granular hot-melt adhesive is cut while being extruded from a disk to a columnar shape. Depending on the difference between the inside and outside cooling rates, a depression having a depressed surface is generated due to a difference in cooling rate between the inside and outside, and the tendency to be hardly formed into a sphere close to a true sphere having excellent fluidity becomes strong. However, the melt viscosity at 180 ° C. of the hot melt adhesive composition used is 1100 cp.
s or less, and the difference between the heating temperature in the extruder and the water temperature in the cooling water tank is 115 ° C. or less, so that the hot melt adhesive is difficult to mold as compared with the hot melt adhesive composition having a high melt viscosity. Even when the agent composition is used, it can be formed into a spherical shape close to a true sphere having excellent fluidity. The difference between the heating temperature in the extruder and the water temperature in the cooling water tank is preferably 9
The temperature is 0 ° C. or lower, more preferably 70 ° C.

[0025] The granular hot melt adhesive thus obtained may be, if necessary, for example, wax powder,
Surface treatment may be carried out using various anti-adhesive agents such as emulsion type wax, metal soap, silicone release agent and the like.

(Function) In the method for producing a granular hot-melt adhesive according to the first aspect of the present invention, as described above, the heating temperature of the hot-melt adhesive composition which is heated and kneaded by an extruder and extruded into a rod shape is reduced. Since the temperature is controlled to 125 ° C or lower, the granular hot melt adhesive extruded and cut into a rod during the cooling process expands, cools while being formed into a spherical shape by its internal stress, and is a true sphere having excellent fluidity. It is possible to granulate a granular hot melt adhesive close to the above. Further, the particle size of the obtained granular hot melt adhesive can be adjusted by arbitrarily controlling the size of the mold cavity.

The method for producing a granular hot melt adhesive according to the second aspect of the present invention is, as described above, a hot melt adhesive composition used in the method for producing a granular hot melt adhesive according to the first aspect of the invention. Elastic modulus of 50-50
Since it is 00 Pa, the cut granular hot melt adhesive expands, cools while being shaped into a sphere by its internal stress, and easily granulates a granular hot melt adhesive having good fluidity and close to a perfect sphere. You can do it.

In the method for producing a granular hot melt adhesive according to the third aspect of the present invention, the difference between the heating temperature in the extruder and the water temperature in the cooling water tank is controlled within 115 ° C. In the process, the granular hot melt adhesive extruded and cut into a rod expands, cools while being shaped into a sphere by its internal stress, and granulates a granular hot melt adhesive with good fluidity and close to a perfect sphere. You get.
Furthermore, the larger the particle size of the obtained granular hot-melt adhesive, the easier it is to shape into a spherical shape close to a true sphere, and the particle size can be controlled to an arbitrary particle size by the size of the mold cavity, so that the particle size during pneumatic transportation can be reduced. It can easily produce a granular hot-melt adhesive having a relatively large particle size and good fluidity.

The method for producing a granular hot-melt adhesive according to the invention of claim 4 is, as described above, a hot-melt adhesive composition used in the method for producing a granular hot-melt adhesive according to claim 3 of the invention. Although the melt viscosity at 180 ° C. is 1100 cps or less, the cut granular hot melt adhesive expands, cools while being shaped into a sphere by its internal stress, and forms a true sphere with good fluidity. A close granular hot melt adhesive can be easily granulated.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Examples 1 to 5, Comparative Examples 1 and 2) Using a granular hot melt adhesive manufacturing apparatus as shown in FIG.
As a hot melt adhesive composition, an ethylene-vinyl acetate copolymer (EVA) -based hot melt adhesive (trade name “Esdine”, represented by a product number in the table) manufactured by Sekisui Chemical Co., Ltd. shown in Table 1 was used. Molded under the molding conditions shown in Table 1,
A granular hot melt adhesive was prepared. First, the hot melt adhesive composition was heated and kneaded in an extruder equipped with a water-cooled temperature controller under a temperature condition of 125 ° C. or less, extruded into a cooling water tank as a rod from a mold, and cut under cooling. To form the hot melt adhesive composition into a spherical shape.

The modulus of elasticity of the EVA hot-melt adhesive used at the temperature in the extruder was measured using a product name "DVA-200" manufactured by IT Measurement Control Co., Ltd., and the sample size was 5
The modulus of elasticity at the temperature in the extruder was determined based on the measured values of viscoelasticity measured in a shear mode of 2 mm × 6 mm × 1 mm (measurement conditions) in a shearing mode, at a rate of temperature rise of 5 ° C./min, and at a frequency of 10 Hz. And shown in Table 1.

The spherical compact was separated from the cooling water and dried to produce a granular hot melt adhesive.

(Examples 6 to 12, Comparative Example 3) An EVA hot melt adhesive (manufactured by Sekisui Chemical Co., Ltd.) shown in Table 2 was manufactured using an apparatus for manufacturing a granular hot melt adhesive as shown in FIG. Under the molding conditions shown in Table 2 to produce a granular hot melt adhesive. The melt viscosity at 180 ° C. of the EVA hot melt adhesive used was measured according to JIS K6.
862, and are shown in Table 2, respectively.

First, the hot melt adhesive composition is heated and kneaded under a temperature condition set according to the hot melt adhesive composition used in an extruder equipped with a water-cooled type temperature controller, and then the hot melt adhesive composition is injected from the mold into the extruder. The hot melt adhesive composition is extruded into a rod shape in a cooling water bath having a temperature condition set so that the difference between the heating temperature of the cooling water bath and the water temperature of the cooling water bath is 115 ° C. or less, and cut under cooling to form the hot melt adhesive composition into a spherical shape. Molding. The spherical compact was separated from the cooling water and dried to produce a granular hot melt adhesive.

In order to evaluate the performance of the granular hot melt adhesives obtained in Examples 1 to 12 and Comparative Examples 1 to 3, the shape and fluidity of the granular hot melt adhesives were evaluated by the following methods. The evaluation results are shown in Tables 1 and 2, respectively.

[Evaluation Method of Shape] From the obtained granular hot-melt adhesive, 10 particles were sampled by random sampling to obtain a sample. The samples were visually observed, and the shape was as follows: ：: All the samples had a shape close to a true sphere or a spheroid, and were smooth particles having no constrictions, depressions, or protrusions, and Δ: The sample was evaluated in three stages: one in which slight protrusions such as mustaches were observed in the sample, and X: one in which the surface was roughened with constrictions, dents and protrusions observed in the majority of the sample.

[Method of Evaluating Fluidity] 100 particles of the obtained granular hot melt adhesive were sprayed on a stainless steel plate having a smooth surface, and one side of the stainless steel plate was fixed on a flat surface on a test stand, and was opposed to the side. Gently lift the other side to make a 10 ° slope with the test bench, count the number of particles of the granular hot-melt adhesive that has rolled down from the stainless steel plate, and calculate the drop rate (number of dropped particles / 100 particles). (Percentage) was calculated, and the evaluation was made in three stages: ：: the drop rate was 90% or more, and X: the drop rate was less than 90%.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

According to the method for producing a granular hot melt adhesive of the present invention, the granular hot melt adhesive obtained has a shape close to a true sphere or a spheroid, It has a smooth surface with no constrictions, dents or protrusions, and can stably produce a granular hot-melt adhesive with a relatively large arbitrary particle size. It is less likely to be deformed by compression and can suppress blocking between granular hot melt adhesives. Therefore, it has good fluidity during pneumatic transportation.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one example of a production apparatus used in a method for producing a granular hot melt adhesive of the present invention.

FIG. 2 is an enlarged cross-sectional view of a portion (circle) of the circle between the extruder 1 and the separating device 5 on the right side of FIG. 1 (the tip of the mold 12, the granulating device 3 and the cooling water tank 4). FIG. 4 is an explanatory view conceptually showing the state of (1).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Extruder 12 ... Die 2 ... Hot melt adhesive composition 3 ... Granulating device 31 ... Rotating blade 32 ... Mounting disk 33 ... Drive shaft 4 ... Cooling water tank 41 ... Water supply device 42 ... Drainage and granular hot melt adhesion Discharge device 5… Separation device

Continued on front page F-term (reference) 4J040 DA001 DA051 DA061 DA101 JA07 JB01 LA01 LA06 LA11 QA05 QA09 QB03 QB04

Claims (4)

[Claims] 1. A method for producing a granular hot melt adhesive in which a hot melt adhesive composition heated and kneaded by an extruder and extruded into a rod shape is cut in a cooling water bath under cooling and molded into a spherical shape. A method for producing a granular hot melt adhesive, wherein the heating temperature of the hot melt adhesive composition which is heated and kneaded by a machine and extruded into a rod shape is 125 ° C. or less. 2. An elastic modulus of the hot melt adhesive composition at an extruder temperature of 50 to 5000 Pa.
A method for producing the granular hot melt adhesive according to the above. 3. A method for producing a granular hot melt adhesive in which a hot melt adhesive composition heated and kneaded by an extruder and extruded into a rod shape is cut in a cooling water bath under cooling and molded into a spherical shape. A method for producing a granular hot melt adhesive, wherein the difference between the heating temperature in the machine and the water temperature of the cooling water tank is within 115 ° C. 4. The hot melt adhesive composition of claim 1, wherein
The method for producing a granular hot melt adhesive according to claim 3, wherein the melt viscosity at 1C is 1100 cps or less.