JP2002338939A - Blocking-preventing method for adhesive hot melt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blocking-preventing method for a hot melt having an adhesive property during storage, or the like, capable of preventing the blocking with a relatively simple operation and making a mixing of impurities as less as possible. SOLUTION: A surface of a cooled and solidified hot melt block having an adhesive property is elastically enlarged. After particulates, for example, powders of calcium carbonate, silica, talc, zeolite, or the like, for preventing deposition are deposited on the enlarged surface, the enlarged surface is returned to the state before enlarged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing blocking during storage of a hot-melt adhesive having tackiness.

[0002]

2. Description of the Related Art Thermoplastic adhesives, especially hot melt adhesives, are widely used in various industrial fields. This hot-melt adhesive may stick to other objects or another hot-melt adhesive during transportation or storage if it is naked, or may pick up dust or foreign matter that has come in contact with it. It is common to wrap it in a pattern paper or a non-sticky film or the like for dealings.

[0003]

A method which has been conventionally adopted as a packaging method capable of preventing the adhesion of the above-mentioned hot melt adhesives (hereinafter abbreviated as "hot melt"), that is, the so-called blocking, includes, for example, an internal Is a method of pouring hot melt into a container made of paper, plastic, aluminum plate, etc. that has been peeled off with silicone resin etc., cooling and solidifying, while hot water extruded in a high-temperature molten state while spraying cold water from the outside A method of wrapping with a film, a method of co-extruding a non-adhesive component in a pod shape on the outside when extruding an adhesive hot melt into water,
After cooling the hot melt, an organic powder such as wax or an inorganic powder such as talc is uniformly attached to the surface of the hot melt.

However, all of the above-mentioned conventional methods have problems and cannot be said to be sufficiently satisfactory. In other words, the method of pouring hot melt into a container made of paper, plastic, aluminum plate, etc., the inside of which has been peeled with silicone resin etc., and cooling and solidifying it, requires disposing of paper and plastic coated with silicon at the time of use. However, these materials have a problem that they cannot be recycled because they have silicon.

[0005] Also, while spraying cold water from the outside,
The method of wrapping a hot melt extruded in a high-temperature molten state with a film requires complicated equipment and has a limitation on the film thickness.If the film is too thin, the film is damaged by heat and sticks to the surface The part is exposed. If the film is made thick to prevent this, there is a problem that the amount of impurity components other than the components of the hot melt increases. Moreover, this method requires a certain heat resistance of the film used, and as a result, when using a hot melt,
Since the tank temperature must be raised to an unnecessary temperature, there is a problem that it is uneconomical.

Further, when extruding an adhesive hot melt into water, a method of co-extrusion of a non-adhesive component to the outside in a pod shape requires a large thickness of a portion belonging to the outer sheath due to the accuracy of co-extrusion. Therefore, there is a problem that the amount of impurities increases as a result. Also, the apparatus used in this method is special and uncommon, so that it is expensive.

Next, the method of uniformly adhering an organic powder such as wax or an inorganic powder such as talc to the surface of the hot melt after cooling the hot melt has a very small amount as an impurity component. When applied to a sticky hot melt that is soft and easily deformed, there is a problem that the powder is buried in the surface of the hot melt, so that blocking occurs during long-term storage or transportation.

Accordingly, the present invention improves the problems of the above-mentioned conventional method for preventing sticky hot melt from blocking, and can prevent blocking with a relatively simple operation and can minimize the amount of impurities as much as possible. The task is to provide a method.

[0009]

In order to solve the above problems, the present invention employs the following configuration. That is, the method for preventing blocking of the adhesive hot melt according to the present invention elastically enlarges the surface of the hot-melt block having the adhesiveness that has been cooled and solidified, and adheres the anti-wear powder to the enlarged surface. After that, the surface of the hot melt block is coated with the powder at a high density by returning the enlarged surface to a state almost before the enlargement. The enlargement ratio of the surface depends on the material of the hot melt and the like, but is usually preferably in the range of 5 to 200%.

In this blocking prevention method, an anti-wear powder is adhered while the surface of a hot-melt block having tackiness is once enlarged, and then the surface area of the hot-melt block is substantially reduced to a state before the powder is adhered. Since the powder is returned, the density of the powder after the return is greatly improved. For this reason, the surface having tackiness is hardly exposed, and blocking can be prevented for a long time.

[0011] Since the adhesive hot melt is generally soft, the conventional anti-blocking method of simply adhering an anti-wear powder to the surface of the hot melt is difficult when the storage or transportation is performed for a long time or at a high temperature. However, if a load is excessively applied for some reason, the hot melt itself is deformed, and the surface is partially stretched to increase the particle interval between the powders. As a result, the adhesive surface is exposed and blocking occurs. The present invention has been completed on the basis of such knowledge, and predicts the load applied to the hot melt in advance, and attaches the powder in a state where the predicted load is applied,
Even if a load is applied during storage or the like to increase the surface area of the hot melt, the powder is kept in a sufficiently densely distributed state. Therefore, blocking is effectively prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below. FIG. 1 specifically illustrates an embodiment of the present invention. A plate-shaped or rod-shaped hot melt block B is gripped by chucks 1 and 1 and pulled in a predetermined direction to increase the surface area thereof. In this state, as shown in the figure, the powder P for anti-wear is sprinkled on the enlarged surface to adhere. After the powder is attached to one surface, the block is turned upside down, and the surface P is similarly enlarged to attach the powder P. At the time of sprinkling the powder on the surface, the powder is also sufficiently sprinkled onto the peripheral portion of the block B and adhered.

When the powder is sufficiently adhered to the entire surface of the block B, the block B is left as it is. Then, the block B quickly returns to the original state due to elasticity, and the enlarged area contracts to almost the size before the enlargement. Since the anti-wear powder is adhered to the surface in an enlarged state, the density of the powder is greatly improved by the shrinkage of the surface area, and the adhesive surface of the hot melt is coated at a high density. Therefore, no blocking occurs even when an external pressure is applied. Block B
Since the outer peripheral surface portion does not adhere the powder in an enlarged state, the density of the powder does not improve so much at the time of shape restoration, but if this portion is sufficiently dusted and adhered after the restoration, Good.

Next, FIG. 2 shows a method of enlarging the surface different from the above. In this example, a hot melt block B is placed on the base plate 2 and at least the area of the hot melt block when enlarged from above. A weight 3 having a surface releasability having a larger area is placed thereon to expand the surface of the hot melt block under pressure. When the hot melt block is spread by the load of the weight 3, the weight is removed, and the powder for anti-wear is sprinkled and adhered to the surface. If a powder layer is also formed on the floor plate 2, the powder can be attached to both surfaces of the block by one operation. This method
You only need to prepare a weight with an appropriate surface release,
It has the advantage that it is economical and can easily achieve its intended purpose.

FIG. 3 shows a further different method. In this method, the powder P for prevention is laminated on the conveyor 4 moving in the direction of arrow A, and the hot melt block B is placed thereon. And a pressing plate 5 which makes a substantially circular motion in a horizontal plane
Then, the block is rotated while being pressed on the conveyor. As a result, for example, the outer diameter of the spherically rounded hot melt block is expanded, and the powder adheres to the surface while rotating. The conveyor 4 is preferably made of a material that can easily hold powder, such as a relatively coarse cloth. Further, it is preferable that a large number of fine irregularities capable of holding powder are formed on the pressing surface of the pressing plate 5. 6 is a screen for supplying the powder P onto the conveyor, and 7 is a stopper for determining a lower limit position of the pressing plate. Although the block is spherical in the illustrated example, the shape of the block is not limited to this, and may be another shape such as a round bar shape.

The area expansion ratio of the block depends on the properties of the hot melt, but is preferably 5 to 200%. Various organic powders or inorganic powders can be used as the anti-wear powder. Examples of preferred powders and particle sizes include, for example, inorganic fine powders such as calcium carbonate, silica, talc, and zeolite having an average particle size of 0.05 to 30 microns, and superfine particles having an average particle size of 5 to 30 millimicrons. Fine powdered silica, waxes having an average particle size of 1.0 to 200 microns, fatty acid metal salts, amide compounds, or simple substances selected from polyolefin-based, polyamide-based or polyester-based polymers or a mixture thereof, such as hot It is only necessary to use a material which does not significantly deteriorate the performance of the melt and is hardly deteriorated. Although the preferred particle size of the powder is as described above, generally, for example, a powder passing through 40 mesh or the like can be suitably used. Various methods other than those described above can be adopted as a method for expanding the area of the hot melt block and a method for attaching the powder.

This method makes it possible to compensate for the imperfections of the conventional anti-deposition treatment and to carry out the method as a more effective processing method. That is, first, the tacky hot melt is tentatively subjected to anti-adhesion treatment by powder adhesion as in the prior art, and then subjected to the treatment according to the present method to obtain a product having higher anti-adhesion properties. Obtainable.

Furthermore, the present invention is compatible with any type of surface tacky hot melt adhesive treatment. These hot melts are generally composed of a base polymer and an adhesive resin, and are partially added with a plasticizer or a wax-like low-molecular-weight additive. Examples thereof are shown below. There are compounds. That is, as the base polymer, EVA, polyalphaolefin, AP
P, olefin polymers such as polyethylene, SBS, S
Examples include styrene block copolymers such as IS, SEBS, and SEPS, and other polyamides and polyesters.
Examples of the adhesive resin include rosin and esters thereof, derivatives thereof, petroleum resins (aliphatic, alicyclic, aromatic and copolymers thereof) and hydrogenated products thereof, and terpene resins. And their hydrogenated products. Further low-molecular-weight additives include general plasticizers,
Examples thereof include paraffinic, naphthenic and aromatic mineral oils, paraffinic and synthetic waxes, and hydrogenated vegetable oils.

[0019]

EXAMPLES In order to test the anti-blocking effect of hot melt, three kinds of samples shown in Table 1 were prepared.

[0020]

[Table 1]

Example 1 The EVA-based hot melt adhesive of Sample 1 (having a size of 15 × 25 mm, a thickness of 5 mm, and a mini slat) did not block at 20 ° C., but often blocked during transportation in summer. In order to verify this phenomenon, 20 kg bags of this hot melt were stacked in a heat-insulated warehouse at 40 ° C. and stored for 5 days. After observing the blocking state, only slight blocking occurred up to the upper three bags. In the case of 4 bags (5 stacks), the hot melt of the bottom bag caused blocking, and they did not separate again when a force was applied.

This phenomenon is caused by placing 50 grams of hot melt mini slats in a 100 ml polyethylene beaker, placing an empty beaker from above, placing a weight of 1 kg or more in the beaker, applying a load, and placing the load in an oven at 40 ° C. By inserting, it can be reproduced in a laboratory.

The hot melt sample was heated to 40 ° C. and passed between upper and lower rollers 8 and 8 of which the entire surface was cut with a linear pressure of 15 kg and 20 kg as shown in FIG. At the same time, powder (calcium carbonate powder, 80 mesh-passed product) was sprayed on this roller so that the powder was uniformly and strongly applied to the hot melt. Thereafter, excess powder was removed through a sieve.
The average powder adhesion amount was 0.2 wt% with respect to the hot melt in each case. When 50 grams of this sample was stored under the same laboratory conditions as above, the linear pressure was 15 kg.
In the case where the powder was applied, the coating was slightly blocked, but in the case where the powder was applied at a linear pressure of 20 Kg, the blocking did not occur even after storage for 10 days.

(Example 2) The SBS hot melt (spherical shape having a diameter of about 20 mm) of Sample 2 is such that the hot melts only lightly contact each other at room temperature without any kind of anti-adhesion treatment so that they adhere to each other. There is a surface tack. This relatively hard hot melt has a rubber elasticity that deforms when a force is applied, but recovers to an original spherical shape as soon as the force is released.

This hot melt was passed through a cloth belt conveyor 4 as shown in FIG. This belt conveyor has a plate 5 on the entire surface of which a mesh is cut above the belt and has a surface parallel to the belt surface. The plate 5 vibrates at a high speed so as to draw a small circle. Fix the distance between the belt and the plate parallel to it to 15 mm,
The hot melt is passed through this gap while being compressed and deformed together with the powder (polyethylene wax, 40 mesh passing product).

According to this process, 50 g of the hot melt having the powder uniformly applied to the surface was placed in a polyethylene beaker and pressurized and stored in the same manner as in Example 1; however, even after storage for 10 days, blocking occurred. Did not. The amount of powder attached to the hot melt was 0.1 wt% or less.

Example 3 The SIS-based hot melt (spherical shape having a diameter of about 20 mm) of Sample 3 is very soft and has a very strong surface tack. Using a belt similar to that of Example 2 above, this hot melt was passed through together with powder (polyethylene wax, 40 mesh-passed product) with the distance between the belt and the plate fixed at 10 mm. This hot melt did not cause blocking under the same storage conditions as in Example 1. The amount of powder adhering to the hot melt was 0.2 wt% or less.

[0028]

As is evident from the above description, the method for preventing sticky hot melt blocking according to the present invention can easily carry out blocking prevention treatment using a simple apparatus, The amount of impurities in the melt can be minimized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment different from the above.

FIG. 3 is an explanatory diagram of still another embodiment.

FIG. 4 is an explanatory view of still another embodiment.

[Explanation of symbols]

 Reference Signs List 1 chuck 2 base plate 3 weight 4 belt conveyor 5 disk 6 screen 8 roller B hot melt block P powder for anti-wear

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C09J 177/00 C09J 177/00 191/06 191/06 F term (reference) 4J040 BA182 BA201 DA002 DA101 DE021 DM011 DN031 DN071 ED001 ED002 EG001 EG002 HA196 HA306 HA356 HB24 HC11 JA06 JB01 KA03 KA42 QA09

Claims (3)

[Claims] 1. A surface of a hot-melt block having adhesiveness that has been cooled and solidified is elastically enlarged, and a powder for anti-wear is attached to the enlarged surface, and then the enlarged surface is generally enlarged. A method for preventing blocking of a sticky hot melt, wherein the surface of the hot melt block is coated with the powder at a high density by returning to a previous state. 2. The method for preventing blocking of an adhesive hot melt according to claim 1, wherein the enlargement ratio of the surface area is 5 to 200%. 3. The powder is an inorganic fine powder such as calcium carbonate, silica, talc, zeolite or the like having an average particle diameter of 0.05 to 30 microns, ultra-fine powder silica having an average particle diameter of 5 to 30 millimicrons, Waxes having an average particle size of 1.0 to 200 microns, metal salts of fatty acids, amide compounds, or simple substances selected from polyolefin-based, polyamide-based or polyester-based polymers or mixtures thereof are used as powders for antiwear. The method for preventing blocking of an adhesive hot melt according to claim 1 or 2, which is used.