Abstract:
The invention is intended to provide a brush which, while maintaining the superiority of animal hairs in paint holding and discharging performance, is free from the stiffening of the roots of bristles  4  and the expansion of the tips thereof even after its use for applying a water paint, and a method for manufacturing of this brush. To achieve the object stated above, the invention uses as its bristles  4  animal hairs whose pH count is adjusted to be neutral or alkaline.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a brush most suitable for applying water paints and a method for manufacturing the same.  
         [0003]     2. Description of the Related Art  
         [0004]     Brushes can be broadly classified into two types by the material of bristles. One is animal hair type brushes using hairs of goats, horses, pigs or the like for the bristles and the other, synthetic fiber type brushes whose bristles are made of a synthetic resin, such as polybutylene terephthalate (PBT).  
         [0005]     The animal hair type brushes, because of the effect of cuticles which make the bristle surface relatively rugged, are superior in the performance to hold or discharge the paint, and subtly differ in resilience with the kind of animal or the region of the animal body from which the hairs were clipped off. These characteristics provide the advantage that brushes widely varying in characteristics can be produced by choosing the type of animal hair fit for each specific purpose.  
         [0006]     On the other hand, synthetic fiber type brushes have an advantage of high resistance to wear, and are coming into increasing use today. However, since the bristles of synthetic fiber type brushes, unlike animal hair bristles, have no cuticles on the surface, which is therefore smooth, they are less effective in the performance to hold or discharge the paint and difficult to be subtly differentiated in resilience. Therefore, in some respects, such as the ease of paint application and the efficiency of work, they are inferior to animal hair brushes.  
         [0007]     At the same time, paints also have two broad types, oil paints and water paints. Oil paints, diluted with a volatile organic compound (VOC) solvent such as thinners, have an advantage of excellent coating performance. However, on account of the destructive effect of the VOC contained in such oil paints on the global environment, as well as its adverse influence on human health, now there is a gradually tightening restraint on their use.  
         [0008]     By contrast, water paints, which are not diluted with thinners or any other VOC, have the advantages of friendliness to the global environment and relatively little adverse effects on human health. Moreover, water paints, which were previously inferior to oil paints in coating performance, are now comparable to oil paints in this respect as a result of technical improvements over the recent years. Furthermore, water paints have another advantage of drying faster than oil paints. On account of these advantages, water paints tend to increasingly replace oil paints in many areas of application.  
         [0009]     Incidentally, for applying a water paint, usually a synthetic fiber type brush is used more often than an animal hair type brush, because an animal hair type brush can no longer serve as a brush after it is used for applying a water paint even once and accordingly is very uneconomical. Thus, the paint readily finds its way between the bristles of an animal hair type brush because of their surface ruggedness, and once a fast drying water paint sticking to the bristles becomes dry, it cannot be easily removed even if washed with water. For this reason, as shown in  FIG. 2 , the root portion  1   a  of the bristles  1  is stiffened, or the tips  1   b  of the bristles expand in a fan shape.  
         [0010]     If the root part  1   a  of the bristles  1  is stiffened, it will become impossible to move the brush in the ways needed for painting work, such as returning or otherwise handling it, and the painting work will be made extremely difficult. Or if the tips  1   b  of the bristles  1  expand, it will become impossible to finish the coat neatly. Thus, if an animal hair type brush is used for applying a water paint, in most cases that brush will have to be thrown away after being used only once, and therefore it is common sense among persons skilled in the art that the use of an animal hair type brush for the application of a water paint is economically unjustifiable.  
         [0011]     On the other hand, a synthetic fiber type brush, as its bristles have no unevenness on the surface, does not allow the paint to readily stick to the bristles and, even when it is used for applying a water paint, can be cleared of the paint by washing with water or the like. For this reason, the root portion of the bristles is not stiffened. Nor do the tips  1   b  of the bristles  1  expand. Thus, synthetic fiber type brushes can be used a number of times even for applying a water paint, and therefore are economical. Because of their advantage, persons skilled in the art think synthetic fiber type brushes are more suitable for use in applying a water paint.  
         [0012]     To add, since it is taken for granted among persons skilled in the art that synthetic fiber type brushes are more suitable for use in applying a water paint, nothing was found in prior technical literature about animal hair type brushes which could be effectively used for this purpose.  
         [0013]     As stated above, synthetic fiber type brushes, because of their poorer performance in holding or discharging the paint, have to be dipped in the paint more often during the painting work and accordingly are detrimental to the working efficiency. Furthermore, since the subtle difference in resilience, which animal hairs can provide, is not available, synthetic fiber type brushes are inferior to animal hair type brushes in the ease of paint application as well.  
       SUMMARY OF THE INVENTION  
       [0014]     An object of the present invention is to provide a brush which, while maintaining the superiority of animal hairs in paint holding and discharging performance and is free from the stiffening of bristle roots and the expansion of bristle tips even after its use for applying a water paint, and a method for manufacturing this brush.  
         [0015]     To achieve the object stated above, the invention has the following features.  
         [0016]     According to a first aspect of the invention, a brush uses as its bristles animal hairs whose pH count is kept neutral or alkaline.  
         [0017]     According to a second aspect of the invention, the brush according to the first aspect has bristles of which 1% to 40% are made of a synthetic fiber material.  
         [0018]     According to a third aspect of the invention, the bristles of a brush are washed with an alkaline washing liquid after they are fixed to the stem of the brush and dried after that.  
         [0019]     According to a fourth aspect of the invention, the brush according to the third aspect, the bristles are washed by applying vibration of high frequency to the alkaline washing liquid. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  shows an overall view of a brush, which is a preferred embodiment of the present invention; and  
         [0021]      FIG. 2  shows an overall view of a conventional brush.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     As shown in  FIG. 1 , a brush has bristles  4  fixed to one end of its stem  2  via a holding member  3 . In this embodiment of the invention, the bristles  4  are made of animal hairs. It has to be noted that these bristles  4  are not merely carded, but also washed with an alkaline washing liquid and dried.  
         [0023]     Since alkaline washing liquids are highly effective in removing dirt, washing animal hairs with an alkaline washing liquid clear the hairs of fine dirt and fat stuck to their surface. As a result, the surface is improved in sliding smoothness to a degree comparable to synthetic fiber bristles. This surface smoothness makes it difficult for the water paint to stick to the bristles, and this in turn makes it easier for the water paint to be removed when washed with water or the like.  
         [0024]     Furthermore, while animal hairs are slightly acid by nature, they are made neutral or alkaline by washing with the alkaline washing liquid. Thus, in this embodiment of the invention, the bristles  4  are made of animal hairs which are made neutral or alkaline. The reason for this neutralization of the bristles  4  will be explained below. It was found out by experiment that water paints are hardened when they come into contact with an acid substance. Also, pH assessment of animal hairs revealed their slight acidity. These findings suggest that when an animal hair type brush is used for applying a water paint, its bristles  4  are readily stiffened because of the slight acidity of the bristles  4 .  
         [0025]     In view of this point, in this brush embodying the invention, the bristles  4  are made neutral or alkaline by washing the bristles  4  in advance with an alkaline washing liquid. By making the bristles  4  neutral or alkaline in this way, even if the bristles  4  come into contact with a water paint, hardening of the paint can be delayed. Moreover, since the surface of the bristles is smoothed as stated above, the water paint stuck to the bristles can be efficiently removed by washing them with water or the like. Therefore, the root portion  4   a  of the bristles  4  can be prevented from becoming stiff and the tips  4   b  of the bristles  4  from expanding.  
         [0026]     The alkalinity of the washing liquid may be either weak or strong. It needs only to be alkaline at all, though use of a washing liquid of strong alkalinity may adversely affect the resilience of the bristles. Therefore in this embodiment, the bristles are washed with a weak alkaline washing liquid of 8 to 10 in pH, which is further diluted with water.  
         [0027]     Further, the washed bristles need only to be non-acid. They may be either neutral or alkaline.  
         [0028]     In addition, since in this embodiment the washing clears the surface of the bristles of fine dirt and fat stuck thereto as described above, the water paint does not stick to any dirt. If the water paint sticks to dirt and hardens as it is, the bristles  4  may become stiff. However, if the bristle surface is fully cleared of dirt in advance as in this embodiment, no water paint will stick to and stiffen the bristles  4 . Therefore, the problems of the hardening of the paint stuck to the root portion  4   a  of the bristles  4  and the expansion of the tips  4   b  of the bristles  4  can be prevented more effectively.  
         [0029]     Incidentally, the washing of the bristles  4  with an alkaline washing liquid as stated above exhibited no significant impact, if any, on the water-absorbance of the animal hairs or the ease of returning or otherwise handling of the brush.  
         [0030]     Next, a method for manufacturing this brush will be described below.  
         [0031]     First, animal hairs are trimmed to a prescribed length, and put together into bundles each of the size required for a brush. And each of these bundles of bristles  4  is fixed to the holding member  3 . After the bristles  4  are fixed to the holding member  3  in this way, the holding member  3  is fixed to one end of the stem  2 .  
         [0032]     After fixing the bristles  4  to the end of the stem  2  via the holding member  3 , the bristles  4  are soaked in and washed with an alkaline washing liquid. This alkaline washing liquid may be either weak or strong in alkalinity. However, since the use of a washing liquid of strong alkalinity may adversely affect the resilience of the bristles as stated above, the bristles are washed with a weak alkaline washing liquid of 8 to 10 in pH, which is further diluted with water, in this embodiment.  
         [0033]     Further, this embodiment may use an ultrasonic washing machine for washing the bristles  4 . This ultrasonic washing machine, which is a known apparatus, is provided with a vessel for keeping the washing liquid and a vibrating mechanism for vibrating the washing liquid in the vessel tens of thousands of times a second. As washing the bristles  4  with such an ultrasonic washing machine serves to transmit the vibration to the bristles via the washing liquid, each individual bristle is thoroughly cleared of fine dirt and fat stuck to it. Moreover, as the vibration brings each individual bristle into contact with the alkaline washing liquid, the pH count of the bristles can be efficiently changed from slight acidity to neutrality or alkalinity.  
         [0034]     To add, though an ultrasonic washing machine is used for washing the bristles in this embodiment, the use of any other means than an ultrasonic washing machine is in no way inconsistent with the invention.  
         [0035]     As described above, after soaking the bristles  4  in the alkaline washing liquid for a certain length of time and washing them with it, the bristles are taken out of the washing liquid and dried. When the bristles are fully dry, the brush is completed.  
         [0036]     Incidentally, it is also conceivable to soak animal hairs in an alkaline washing liquid before fixing the bristles  4  to the stem  2 . Yet, washing the bristles  4  with an alkaline washing liquid before fixing them to the stem  2  might result in some change in the characteristics of the hairs, which would make it more difficult to keep them neatly together and accordingly to fabricate the brush. However, washing the bundled bristles after they are fixed to the stem in advance would eliminate the risk of letting the bristles become disorderly and more difficult to be fabricated into a brush.  
         [0037]     Further, though the bristles in this embodiment are supposed to consist of animal hairs 100%, the bristles  4  of 100% animal hairs may prove insufficient in resilience. For instance, it was actually revealed by experiment that, while an increased concentration of the washing liquid served to enhance its washing effect, the resilience of the bristles  4  was somewhat lost. In view of this finding, bristles consisting of synthetic fibers, such as polybutylene terephthalate, were mixed with animal hairs in a proportion of about 30%. Synthetic fiber bristles are unaffected in resilience even if washed with an alkaline washing liquid. Therefore, mixing synthetic fibers having some resilience with animal hairs to form the bristles  4  would keep the overall resilience of the bristles greater than that of a brush of 100% animal hairs. Moreover, since synthetic fiber bristles are intrinsically neutral, their mixture with animal hairs would not invite hardening of the water paint.  
         [0038]     However, if the proportion of synthetic fiber bristles surpasses 30%, the unique subtleness of animal hairs in painting performance will be more or less lost. Therefore, it is advisable for the proportion of synthetic fibers mixed with animal hairs to be between 1 and 30%, never to surpass 40%.  
         [0039]     According to the first aspect of the invention, even if the brush is used for applying a water paint, the root portion of its bristles can be prevented from becoming stiff and its tips from expanding. Also the superiority of animal hairs in the performance to hold or discharge the paint is maintained. Therefore, while retaining the unique advantages of animal hairs, the brush can be used repeatedly for the application of a water paint.  
         [0040]     According to the second aspect of the invention, the resilience of the bristles can be maintained.  
         [0041]     According to the third aspect of the invention, the bristles can be kept neatly together.  
         [0042]     According to the fourth aspect of the invention, the bristles can be efficiently cleared of fine dirt and fat stuck to their surface. Furthermore, as vibration brings each individual bristle into contact with the alkaline washing liquid, the pH count of the animal hairs can be efficiently changed from slight acidity to neutrality or alkalinity.  
         [0000]     (Description of Symbols)  
         [0000]    
       
           2  Stem  
           3  Holding member  
           4  Bristle  
           4   a  Root portion  
           4   b  Tips